Justification for Administrative Rule Adoption

Boilers
16 TAC Chapter 65, amendments at Subchapter R, §65.607 and §65.611

The Texas Commission of Licensing and Regulation (Commission) adopts amendments to existing rules at 16 Texas Administrative Code, Chapter 65, Subchapter R, §65.607 and §65.611, regarding the Boilers program, without changes to the proposed text as published in the May 11, 2018, issue of the Texas Register (43 TexReg 2902). The rules will not be republished.

The adopted rules make a technical clarification and an editorial correction. The American Society of Mechanical Engineers (ASME), made a change in a national standard, the Section 1 rule on power boilers, that makes a rule amendment necessary. In addition, two instances of an editorial change are made to the boiler’s expansion tank pressure rating requirement. The adopted rules are necessary to allow for the Texas Department of Licensing and Regulation (Department) to approve the installation of newer boilers built to the new standard and to maintain accurate safety requirements.

The adopted amendments to §65.607 specify that boilers having more than 500 square feet of bare tube water heating surface must have two or more safety valves; and make an editorial correction by changing the language from “lower” to “greater.”

The adopted amendment to §65.611 makes an editorial correction by changing the language from “lower” to “greater.”

The Department drafted and distributed the proposed rules to persons internal and external to the agency. The proposed rules were published in the May 11, 2018, issue of the Texas Register (43 TexReg 2902). The deadline for public comment was June 11, 2018. The Department received one comment during the 30-day public comment period. The public comment received is summarized below.

Comment--One individual recommended that the proposed change to §65.607(a)(2), which adds the term “bare tube,” should be made in three additional portions of the rules.

Department Response --The Department agrees that the term “bare tube” should be inserted in §65.608(c)(3) and §65.609(d)(3) to describe the water heating surface. The term is not applicable to feeding boilers and therefore is not appropriate to insert in §65.607(b)(2). The changes to §65.608 and §65.609 must be proposed in a subsequent rulemaking to undergo the public comment process; therefore, the Department has made no change to the rule at this time.

The Board of Boiler Rules (Board) met on July 13, 2018 to discuss the proposed rules and the public comment received. The Board recommended adopting the rules without changes.

At its meeting held on July 20, 2018, the Commission adopted the proposed rules without changes as recommended by the Board and the Department.

The amendments are adopted under Texas Occupations Code, Chapter 51 and Health and Safety Code, Chapter 755, which authorize the Commission, the Department’s governing body, to adopt rules as necessary to implement these chapters and any other law establishing a program regulated by the Department.

The statutory provisions affected by the adoption are those set forth in Texas Occupations Code, Chapter 51 and Health and Safety Code, Chapter 755. No other statutes, articles, or codes are affected by the adoption.

Subchapter R. Technical Requirements

§65.607. Power Boilers, Excluding Unfired Steam Boilers and Process Steam Generators.

(a) Safety valves and pressure relief valves.

(1) The use of weighted-lever safety valves, or safety valves having either the seat or disk of cast iron, is prohibited.

(2) Each boiler shall have at least one safety valve and, if it has more than 500 square feet (47 square meters) of bare tube water heating surface or has electric power input more than 1,100 kilowatts, it shall have two or more safety valves. These valves shall be "V" stamped per ASME Code.

(3) Safety valves or pressure relief valves shall be connected so as to stand in the upright position, with spindle vertical. The opening or connection between the boiler and the safety valve or pressure relief valve shall have at least the area of the valve inlet.

(4) The valve or valves shall be connected to the boiler, independent of any other steam connection, and attached as close as practicable to the boiler without unnecessary intervening pipe or fittings.

(5) Except for changeover valves as defined in §65.1(13), other valve(s) shall not be placed:

(A) between the required safety valve or pressure relief valve or valves and the boiler; or

(B) in the discharge pipe between the safety valve or pressure relief valve or valves and the atmosphere.

(6) When a discharge pipe is used, it shall be:

(A) at least full size of the safety valve discharge; and

(B) fitted with an open drain to prevent water lodging in the upper part of the safety valve or discharge pipe.

(7) When an elbow is placed on a safety valve discharge pipe:

(A) it shall be located close to the safety valve outlet; and

(B) the discharge pipe shall be securely anchored and supported.

(8) In the event multiple safety valves discharge into a common pipe, the discharge pipe shall be sized in accordance with ASME Code, Section I, PG-71.

(9) All safety valve or pressure relief valve discharges shall be located or piped to a safe point of discharge, clear from walkways or platforms.

(10) If a muffler is used on a pressure relief valve, it shall have sufficient area to prevent back pressure from interfering with the proper operation and discharge capacity of the valve. Mufflers shall not be used on High-Temperature Water Boilers.

(11) The safety valve capacity of each boiler must allow the safety valve or valves to discharge all the steam that can be generated by the boiler without allowing the pressure to rise more than 6.0% above the highest pressure to which any valve is set, and to no more than 6.0% above the MAWP. For forced-flow steam generators with no fixed steam and waterline, power-actuated relieving valves may be used in accordance with ASME Code, Section I, PG-67.

(12) One or more safety valves on every drum type boiler shall be set at or below the MAWP. The remaining valve(s) may be set within a range of 3.0% above the MAWP, but the range of setting of all the drum mounted pressure relief valves on a boiler shall not exceed 10% of the highest pressure to which any valve is set.

(13) When two or more boilers, operating at different pressures and safety valve settings, are interconnected, the lower pressure boilers or interconnected piping shall be equipped with safety valves of sufficient capacity to prevent overpressure, considering the maximum generating capacity of all boilers.

(14) In those cases where the boiler is supplied with feedwater directly from water mains without the use of feeding apparatus (not to include return traps), no safety valve shall be set at a pressure higher than 94% of the lowest pressure obtained in the supply main feeding the boilers.

(b) Feedwater supply.

(1) Each boiler shall have a feedwater supply, which will permit it to be fed at any time while under pressure, except for automatically fired miniature boilers that meet all of the following criteria:

(A) the boiler is "M" stamped per ASME Code, Section I;

(B) the boiler is designed to be fed manually;

(C) the boiler is provided with a means to prevent cold water from entering into a hot boiler; and

(D) the boiler is equipped with a warning sign visible to the operator not to introduce cold feedwater into a hot boiler.

(2) A boiler having more than 500 square feet (47 square meters) of water heating surface, shall have at least two means of feeding, one of which should be a pump, injector, or inspirator. A source of feed directly from water mains at a pressure of at least 6.0% greater than the set pressure of the safety valve with the highest setting may be considered as one of the means of feeding. Boilers fired by gaseous, liquid, or solid fuel in suspension may be equipped with a single means of feeding water, provided means are furnished for the immediate shutoff of heat input if the feedwater is interrupted.

(3) Feedwater shall not be discharged close to riveted joints of shell or furnace sheets or directly against surfaces exposed to products of combustion or to direct radiation from the fire.

(4) Feedwater piping to the boiler shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler. When two or more boilers are fed from a common source, there shall also be a stop valve on the branch to each boiler between the check valve and the source of supply. Whenever a globe valve is used on the feedwater piping, the inlet shall be under the disk of the valve.

(5) In all cases where returns are fed back to the boiler by gravity, there shall be a check valve and stop valve in each return line, the stop valve to be placed between boiler and the check valve, and both shall be located as close to the boiler as is practicable. Best practice is that no stop valve be placed in the supply and return pipe connections of a single boiler installation.

(6) Where deaerating heaters are not used, best practice is that the temperature of the feedwater be not less than 120 degrees Fahrenheit (49 degrees Celsius), to avoid the possibility of setting up localized stress. Where deaerating heaters are used, best practice is for the minimum feedwater temperature be not less than 215 degrees Fahrenheit (102 degrees Celsius), so that dissolved gases may be thoroughly released.

(c) Water level indicators.

(1) Each boiler, except forced-flow steam generators with no fixed steam and waterline, and high-temperature water boilers of the forced circulation type that have no steam and waterline shall have at least one water gage glass.

(2) Except for electric boilers of the electrode type, boilers with a MAWP over 400 psig (three (3) megapascals) shall be provided with two water gage glasses, which may be connected to a single water column or connected directly to the drum.

(3) Two independent remote level indicators may be provided instead of one of the two required gage glasses for boiler drum water level indication, when the MAWP is above 400 psig (three (3) megapascals). When both remote level indicators are in reliable operation, the remaining gage glass may be shut off, but shall be maintained in serviceable condition.

(4) In all installations where direct visual observations of the water gage glass(es) cannot be made, two remote level indicators shall be provided at operational level.

(5) The gage glass cock connections shall not be less than 1/2 inch nominal pipe size (15 mm).

(6) No outlet connections, except for damper regulator, feedwater regulator, drains, steam gages, or apparatus of such form as does not permit the escape of an appreciable amount of steam or water there from, shall be placed in the pipes connecting a water column or gage glass to a boiler.

(7) The water column shall be fitted with a drain cock or drain valve of at least 3/4 inch nominal pipe size (20 mm). The water column blowdown pipe shall not be less than 3/4 inch nominal pipe size (20 mm), and shall be piped to a safe point of discharge.

(8) Connections from the boiler to remote level indicators shall be at least 3/4 inch nominal pipe size (20 mm), to and including the isolation valve, and at least 1/2 inch (13 mm) OD tubing from the isolation valve to the remote level indicator. These connections shall be completely independent of other connections for any function other than water level indication.

(d) Low-water fuel cutoff and water feeding devices.

(1) All automatically fired steam boilers, except boilers having a constant attendant, who has no other duties while the boiler is in operation, shall be equipped with approved low-water fuel cutoffs.

(A) These devices shall be installed in such a manner that they cannot be rendered inoperative by the manipulation of any manual control or regulating apparatus.

(B) In boilers with a fixed water line, the low-water fuel cutoff devices shall be tested regularly by lowering the water level sufficiently to shut off the fuel supply to the burner when the water level reaches the lowest safe level for operation. Boilers that do not have a fixed water line shall be equipped with a flow sensing device, thermal couple or expansion ring that is listed by a nationally recognized testing agency to prevent burner operation at a flow rate inadequate to protect the boiler unit against overheating.

(C) The low-water cutoff shall be rated for a pressure and temperature equal to or greater than the MAWP and temperature of the boiler.

(D) For High-Temperature Water Boilers requiring forced flow circulation, an approved flow sensing device shall be installed on the outlet, as close to the boiler as possible.

(2) When a low-water fuel cutoff and feedwater pump control is combined in a single device, an additional separate low-water fuel cutoff shall be installed. The additional control shall be wired in series electrically with the existing low-water fuel cutoff.

(3) When a low-water fuel cutoff is housed in either the water column or a separate chamber it shall be provided with a blowdown pipe and valve not less than 3/4 inch nominal pipe size (20 mm). The arrangement shall be such that when the water column is blown down, the water level in it will be lowered sufficiently to activate the lower-water fuel cutoff device.

(4) If a water feed device is utilized, it shall be constructed to prevent feedwater from entering the boiler through the water column or separate chamber of the low-water fuel cutoff.

(e) Pressure gages.

(1) Each boiler shall have a pressure gage that is readable.

(A) The dial of the pressure gage shall be graduated to approximately double the pressure at which the safety valve is set, but in no case, less than one and one-half times this pressure.

(B) The pressure gage shall be connected to the steam space, to the water column, or its steam connection.

(C) A valve or cock shall be placed in the gage connection adjacent to the gage.

(D) An additional valve or cock may be located near the boiler providing it is locked or sealed in the open position.

(E) No other shutoff valves shall be located between the gage and the boiler.

(F) The pipe connection shall be of ample size and arranged so that it may be cleared by blowing down.

(G) For a steam boiler, the gage or connection shall contain a siphon or equivalent device which will develop and maintain a water seal that will prevent steam from entering the gage tube.

(2) Each boiler shall have a valved connection at least 1/4 inch nominal pipe size (6 mm) connected to the steam space for the exclusive purpose of attaching a test gage when the boiler is in service to test the accuracy of the pressure gage.

(f) Stop valves.

(1) Each steam outlet from a boiler (except safety valve connections) shall be fitted with a stop valve located as close as practicable to the boiler.

(2) When a stop valve is located that allows water to accumulate, ample drains shall be provided. The drain shall be piped to a safe location and shall not be discharged on the boiler or its setting.

(3) When boilers provided with manholes or other similar opening that permits access for human occupancy and that are connected to a common steam main, the steam connection from each boiler shall be fitted with two stop valves, with an ample drain between them. The discharge of the drain shall be visible to the operator while manipulating the valves and shall be piped clear of the boiler setting. Best practice is for the first valve to be an automatic nonreturn valve (set next to the boiler), and a second valve of the outside-screw-and-yoke type.

(g) Blowdown connection.

(1) The construction of the setting around each blowdown pipe shall permit free expansion and contraction. These setting openings must be sealed without restricting the movement of the blowdown piping.

(2) All blowdown piping, when exposed to furnace heat, shall be protected by firebrick or other heat-resisting material, and constructed to allow the piping to be inspected.

(3) Each boiler shall have a blowdown pipe, fitted with a valve or cock, in direct connection with the lowest water space. The piping shall be run full size without the use of a reducer or bushings and shall not be galvanized. Cocks shall be of gland or guard type and suitable for the pressure allowed. The use of globe valves shall be in accordance with ASME code.

(4) When the MAWP exceeds 100 psig (700 kilopascals), the piping shall be at least schedule 80 steel and shall not be galvanized. Each blowdown pipe shall be provided with two valves or a valve and cock, such valves and cocks shall be adequate for design conditions of the boiler.

(5) All fittings between the boiler and blowdown valve shall be of steel or extra-heavy malleable iron. In case of renewal of blowdown pipe or fittings, they shall be installed in accordance with the requirements of the applicable section of the ASME code.

(6) It is recommended that blowdown tanks be designed, constructed, and installed in accordance with National Board recommended rules for boiler blowoff equipment.

(h) Boiler external piping. All boiler external piping, as referenced in the ASME code, shall be examined for compliance to the boiler's code of construction and shall be documented in the appropriate block on the inspection report.

(i) Provisions for thermal expansion for High-Temperature Water Boilers.

(1) An airtight tank or other suitable air cushion that is consistent with the volume and capacity of the system shall be installed. Expansion tanks shall be constructed in accordance with the ASME Code, Section VIII, Division 1, and the pressure and temperature ratings of the tank shall be equal to or greater than the pressure and temperature ratings of the system pressure. A pressure relief valve shall be installed with a set pressure at or below the MAWP of the expansion tank. Alternately the boiler pressure relief valve may be used provided the expansion tank's MAWP is equal to or greater than the set pressure of the pressure relief valve.

(2) Provisions shall be made for draining the tank without emptying the system, except for pre-pressurized tanks.

(3) If the expansion tank was originally equipped with a sight glass, the sight glass and sight glass valves shall be in working condition at all times, and the water level shall be maintained as per the manufacturer's recommendations.

§65.611. Heating Boilers

(a) Steam Heating Boilers.

(1) Safety valves.

(A) Each steam boiler shall have one or more safety valves, that are identified with applicable designator with the ASME Certification Mark of the spring pop type, adjusted and sealed to discharge at a pressure not to exceed 15 psig (103 kilopascals). Seals shall be attached in a manner to prevent the valve from being taken apart without breaking the seal. The safety valves shall be arranged so that they cannot be reset to relieve at a higher pressure than the MAWP of the boiler. A body drain connection below seat level shall be provided. For valves exceeding 2 1/2 inch nominal pipe size (65 mm), the drain hole or holes shall be tapped not less than 3/8 inch nominal pipe size (10 mm). For valves 2 1/2 inch nominal pipe size (65 mm) or less, the drain hole shall not be less than 1/4 inch (6 mm) in diameter.

(B) Each safety valve 3/4 inch nominal pipe size (20 mm) or over, used on a steam boiler, shall have a substantial lifting device, which will positively lift the disk from its seat at least 1/16 inch (1.6 mm), when there is no pressure on the boiler. The seats and disks shall be of suitable material to resist corrosion.

(C) No safety valve for a steam boiler shall be smaller than 1/2 inch nominal pipe size (15 mm). No safety valve shall be larger than 4 1/2 inches nominal pipe size (15 mm). The inlet opening shall have an inside diameter approximately equal to, or greater than, the seat diameter.

(D) The minimum relieving capacity of valve or valves shall be governed by the capacity marking on the boiler.

(E) The minimum valve capacity in pounds per hour shall be the greater of that determined by dividing the maximum Btu output at the boiler nozzle obtained by the firing of any fuel, for which the unit is installed by 1,000, or shall be determined on the basis of the pounds of steam generated per hour, per square foot of boiler heating surface as given in §65.615, Exhibit 7. For cast iron boilers, the minimum valve capacity shall be determined by the maximum output method. In every case, the safety valve capacity for each steam boiler shall be such that with the fuel burning equipment installed, and operated at maximum capacity, the pressure cannot rise more than 5psig (35 kilopascals) above the MAWP.

(F) Safety valve piping. No valve shall be placed between the safety valve and the boiler or on the discharge pipe between the safety valve and the atmosphere. When a discharge pipe is used, it shall be full size and fitted with an open drain to prevent water from lodging in the upper part of the safety valve or pressure relief valve or in the discharge pipe. When an elbow is placed on the safety valve discharge pipe, it shall be located close to the valve outlet. The discharge pipe shall be securely anchored and supported, independent of the valve. If a muffler is used on a pressure relief valve, it shall have sufficient area to prevent back pressure from interfering with the proper operation and discharge capacity of the valve.

(G) Safety valves and pressure relief valves shall be installed on the boiler with spindles positioned vertically. The opening or connection between the boiler and any safety valve or pressure relief valve shall have at least the area of the valve inlet.

(2) Feedwater connections.

(A) Feedwater or water treatment shall be introduced into a boiler through the return piping system or through an independent feedwater connection which does not discharge against parts of the boiler exposed to direct radiant heat from the fire. Feedwater or water treatment shall not be introduced through openings or connections provided for inspection or cleaning, safety valve, surface blowoff, water column, water gage glass, pressure gage, or temperature gage.

(B) Feedwater pipe shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler or return pipe system.

(3) Low-water fuel cutoffs and water feeding devices.

(A) All automatically fired steam boilers, except boilers having a constant attendant, who has no other duties while the boiler is in operation, shall be equipped with approved automatic low-water fuel cutoffs installed in such a manner that they cannot be rendered inoperative by the manipulation of any manual control or regulating apparatus.

(B) The MAWP of all low water fuel cutoff devices shall be set at or above the boiler stamped MAWP.

(C) When low-water fuel cutoff and feedwater pump controls are combined in a single device, an additional separate low-water fuel cutoff shall be installed. The additional control shall be wired in series electrically with the existing low-water fuel cutoff.

(D) When a low-water fuel cutoff is housed in either the water column or a separate chamber, it shall be provided with a blowdown pipe and valve, not less than 3/4 inch nominal pipe size (20 mm). The arrangement shall be such that when the water column is blown down, the water level in it will be lowered sufficiently to activate the low-water fuel cutoff device.

(E) If a water feed device is utilized, it shall be constructed to prevent feedwater from entering the boiler through the water column or separate chamber of the low-water fuel cutoff.

(4) Pressure gages.

(A) Each steam heating boiler shall have a pressure gage connected to the device exterior to the boiler. The gage shall be of sufficient capacity to keep the gage tube filled with water and arranged so that the gage cannot be shut off from the boiler except by a cock with tee or lever handle placed in a pipe near the gage. The handle of the cock shall be parallel to the pipe in which it is located when the cock is open.

(B) The scale on the dial of a steam heating boiler pressure gage shall be graduated to not less than 30 psig (207kilopascals) nor more than 60 psig (414 kilopascals). The travel of the pointer from zero to 30 psig (207 kilopascals) pressure shall be at least three inches.

(5) Stop valves.

(A) Single steam heating boilers. When a stop valve is used in the supply pipe connection of a single steam heating boiler, there shall be one used in the return pipe connection.

(B) Supply and return line. Each supply and return line to a steam heating boiler, which may be entered while adjacent boilers are in operation, shall be fitted with either two stop valves with ample drain between or a stop valve and figure 8 blank. The blank shall be installed between the stop valve and the boiler.

(C) Type of stop valve. When stop valves over two inches in size are used, they shall be of the outside screw-and-yoke rising stem type or of such other type as to indicate at a distance whether it is closed or open by the position of its stem or other operating mechanism. The wheel may be carried either on the yoke or attached to the stem. If the valve is of the plug cock type, it shall be fitted with a slow opening mechanism and an indicating device and the plug shall be held in place by a guard or gland.

(6) Bottom blowdown or drain valve.

(A) Bottom blowoff valve. Each steam heating boiler shall have a bottom blowoff connection fitted with a valve or cock, connected to the lowest water space practicable with a minimum size as shown in §65.615, Exhibit 8. The discharge piping shall be full size to the point of discharge. Boilers having a capacity of 25 gallons (95 liters) or less are exempt from these requirements.

(B) Drain valve. Each boiler shall have one or more drain connections, fitted with valves or cocks connecting to the lowest water containing spaces. The minimum size of the drain piping, valves, and cocks shall be 3/4 inch nominal pipe size (20 mm). The discharge piping shall be full size to the point of discharge. When the blowoff connection is located at the lowest water containing space, a separate drain connection is not required.

(C) Minimum pressure rating. The minimum pressure rating of valves and cocks used for blowoff or drain purposes shall be at least equal to the pressure stamped on the boiler, but in no case less than 30 psig (207 kilopascals). The temperature rating of such valves and cocks shall not be less than 250 degrees Fahrenheit (121 degrees Celsius).

(7) Water gage glasses.

(A) Each steam heating boiler shall have one or more water gage glasses attached to the water column or boiler, by means of valved fittings not less than 1/2 inch nominal pipe size (15 mm). The lower fitting shall have a drain valve of the straightway type, with opening not less than 1/4 inch (8 mm) diameter to facilitate cleaning. Gage glass replacement shall be possible under pressure.

(B) Transparent material, other than glass, may be used for the water gage, provided that the material will remain transparent and has proved suitable for the pressure, temperature, and corrosive conditions encountered in service.

(8) Piping, Fittings and Valves.

(A) All piping, fittings and valves on the steam line, shall have a pressure rating equal to or greater than the MAWP of the boiler and a temperature rating of no less than 250 degrees Fahrenheit (121 degrees Celsius).

(B) All piping, fittings and valves other than the steam line, shall have a minimum pressure and temperature rating equal to or greater than the maximum expected pressure and temperature that may be reached.

(b) Hot Water Heating Boilers.

(1) Pressure relief valves.

(A) Each hot water heating boiler shall have at least one pressure relief valve, of the automatic reseating type, identified with the ASME Certification mark with the "V" or "HV" designator ASME Code Symbol, and set to relieve at or below the MAWP of the boiler.

(B) When more than one pressure relief valve is used on a hot water heating boiler, the additional valve or valves shall have a set pressure within a range not to exceed 6 psig (42 kilopascals) above the MAWP of the boiler up to and including 60 psig (414 kilopascals), and 5.0% for those having a MAWP exceeding 60 psig (414 kilopascals).

(C) Pressure relief valves shall be spring loaded and shall be set and sealed, so that they cannot be reset without breaking the seal. A body drain connection below seat level shall be provided. For valves exceeding 2 1/2 inch nominal pipe size (65 mm), the drain hole or holes shall be tapped not less than 3/8 inch nominal pipe size (10 mm). For valves of 2 1/2 inch nominal pipe size (65 mm) or less, the drain hole shall not be less than 1/4 inch (6 mm) diameter.

(D) Each pressure relief valve shall have a substantial lifting device, which will positively lift the disk from its seat at least 1/16 inch (1.6 mm) when there is no pressure on the boiler.

(E) Seats and disks of pressure relief valves shall be made of a suitable material to resist corrosion. No materials likely to fail due to deterioration or vulcanization, when subjected to saturated steam temperature corresponding to capacity test pressure, shall be used for any part.

(F) No pressure relief valve shall be smaller than 3/4 inch nominal pipe size (20 mm) nor larger than 4 1/2 inch nominal pipe size (115 mm) except that boilers having a heat input not greater than 15,000 Btu/hr (4.4 kilowatts) may be equipped with a rated pressure relief valve of 1/2 inch nominal pipe size (15 mm). The inlet opening shall have an inside diameter approximately equal to, or greater than, the seat diameter. In no case shall the minimum opening through any part of the valve be less than 1/4 inch (6 mm) diameter or its equivalent area.

(G) The required steam relieving capacity, in pounds per hour, of the pressure relieving device or devices on a boiler shall be the greater of that determined by dividing the maximum output in Btu at the boiler nozzle obtained by the firing of any fuel for which the unit is installed by 1,000 or shall be determined on the basis of pounds of steam generated per hour per square foot of boiler heating surface as given in §65.615, Exhibit 7. For cast iron boilers the minimum valve capacity shall be determined by the maximum output method.

(H) In every case, the pressure relief valve capacity for each boiler with a single pressure relief valve shall be such that, with the fuel burning equipment installed and operated at maximum capacity, the pressure cannot rise more than 10% above the MAWP. When more than one pressure relief valve is used, the overpressure shall be limited to 10% above the set pressure of the highest set valve.

(I) Pressure relief valve piping. No valve shall be placed between the pressure relief valve and the boiler or on the discharge pipe between the pressure relief valve and the drain. When a discharge pipe is used, it shall be full size and fitted with an open drain to prevent water from lodging in the upper part of the pressure relief valve or in the discharge pipe. When an elbow is placed on the pressure relief valve discharge pipe, it shall be located close to the valve outlet. The discharge pipe shall be securely anchored and supported, independent of the valve. Mufflers shall not be used on hot water heating boilers.

(J) Pressure relief valves and safety valves shall be installed on the boiler with spindles positioned vertically. The opening or connection between the boiler and any pressure relief valve or safety valve shall have at least the area of the valve inlet.

(2) Makeup water connections.

(A) Makeup water or water treatment shall be introduced into a boiler through the return piping system or through an independent makeup water connection, which does not discharge against parts of the boiler exposed to direct radiant heat from the fire. Makeup water or water treatment shall not be introduced through openings or connections provided for inspection or cleaning, pressure relief valve, pressure gage, or temperature gage.

(B) Makeup water pipe shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler, or between the check valve and the piping system.

(3) Low-water fuel cutoffs and water feeding devices.

(A) All automatically fired hot water heating boilers shall have an automatic low-water fuel cutoff that has been designed for hot water service, and it shall be so located as to automatically cut off the fuel supply when the surface of the water falls to a level below the normal waterline established.

(B) The MAWP of all low water fuel cutoff and flow sensing devices shall be set at or above the boiler stamped MAWP.

(C) When low-water fuel cutoff and feedwater pump controls are combined in a single device, an additional separate low-water fuel cutoff shall be installed. The additional control shall be wired in series electrically with the existing low-water fuel cutoff.

(D) When a low-water fuel cutoff is housed in either the water column or a separate chamber it shall be provided with a blowdown pipe and valve not less than 3/4 inch nominal pipe size (20 mm). The arrangement shall be such that when the water column is blown down, the water level in it will be lowered sufficiently to activate the low-water fuel cutoff device.

(E) As there is no normal water line to be maintained in a hot water heating boiler, any location of the low-water fuel cutoff above the lowest safe water level established by the boiler manufacturer is satisfactory.

(F) All automatically fired hot water heating boilers, when installed in a forced circulation system and not under continuous attendance, shall be equipped in the manner described in this subsection. A coil-type boiler or a water-tube boiler requiring forced circulation to prevent overheating of the coils or tubes shall have a flow sensing device which is listed by a nationally recognized testing agency to prevent burner operation at a flow rate inadequate to protect the boiler unit against overheating.

(G) If a water feed device is utilized, it shall be constructed to prevent feedwater from entering the boiler through the water column or separate chamber of the low-water fuel cutoff.

(4) Pressure and Temperature gages.

(A) Each hot water heating boiler shall have a pressure or altitude gage connected to it or to its flow connection, which cannot be shut off from the boiler except by a cock with tee or lever handle placed in a pipe near the gage. The handle of the cock shall be parallel to the pipe in which it is located when the cock is open.

(B) The scale on the dial of the pressure or altitude gage shall be graduated to not less than 1 1/2 nor more than 3 1/2 times the pressure at which the pressure relief valve is set. The gage shall be provided with effective stops for the indicating pointer at the zero point and at the maximum pressure point.

(C) Piping and tubing for pressure or altitude gage connections shall be of nonferrous metal when smaller than 1 inch nominal pipe size (25 mm).

(D) Each hot water heating boiler shall have a thermometer or temperature gage located and connected, that it shall be readable, and shall be located so that it shall at all times indicate the temperature of the water in the boiler at or near the outlet. If placed on the outlet piping, it must be located between the stop valve and the boiler.

(5) Stop valves.

(A) Stop valves shall be located at an accessible point in the supply and return pipe connections near the boiler nozzle of a single hot water heating boiler installation to permit draining the boiler without emptying the system.

(B) When the boiler is located above the system and can be drained without draining the system, stop valves may be eliminated.

(C) Type of stop valve. When stop valves over two inches in size are used, they shall be of the outside screw-and-yoke rising stem type or of such other type as to indicate at a distance whether it is closed or open by the position of its stem or other operating mechanism. The wheel may be carried either on the yoke or attached to the stem. If the valve is of the plug cock type, it shall be fitted with a slow opening mechanism and an indicating device and the plug shall be held in place by a guard or gland.

(6) Drain valve.

(A) Each hot water heating boiler shall have one or more drain connections, fitted with valves or cocks connecting to the lowest water containing spaces. The minimum size of the drain piping, valves, and cocks shall be 3/4 inch nominal pipe size (20 mm). The discharge piping shall be full size to the point of discharge. When the blowoff connection is located at the lowest water containing space, a separate drain connection is not required.

(B) Minimum pressure rating. The minimum pressure rating of valves and cocks used for blowoff or drain purposes shall be at least equal to the pressure stamped on the boiler, but in no case less than 30 psig (207 kilopascals). The temperature rating of such valves and cocks shall not be less than 250 degrees Fahrenheit (121 degrees Celsius).

(7) Provisions for thermal expansion.

(A) Heating systems with open expansion tank- An indoor overflow from the upper portion of the expansion tank shall be provided in addition to an open vent, the indoor overflow to be carried within the building to a suitable plumbing fixture or basement.

(B) Closed heating system.

(i) If the system is of closed type, an airtight tank or other suitable air cushion that is consistent with the volume and capacity of the system shall be installed.

(ii) If the system is designed for a working pressure of 30 psig (207 kilopascals) or less, the tank shall be suitably designed for a minimum hydrostatic pressure of 75 psig (520 kilopascals).

(iii) Expansion tanks for systems designed to operate above 30 psig (207 kilopascals) shall be constructed in accordance with the ASME Code, Section VIII, Division 1, or Section X, and the pressure and temperature ratings of the tank shall be equal to or greater than the pressure and temperature ratings of the system pressure. A pressure relief valve shall be installed with a set pressure at or below the MAWP of the expansion tank. Alternately the boiler pressure relief valve may be used provided the expansion tank's MAWP is equal to or greater than the set pressure of the pressure relief valve.

(iv) Provisions shall be made for draining the tank without emptying the system, except for pre-pressurized tanks.

(v) If the expansion tank was originally equipped with a sight glass, the sight glass and sight glass valves shall be in working condition at all times, and the water level shall be maintained as per the manufacturer's recommendations.

(8) Piping, Fittings and Valves.

(A) All piping, fittings and valves on the boiler supply and return lines shall have a pressure rating equal to or greater than the MAWP of the boiler and a temperature rating of no less than 250 degrees Fahrenheit (121 degrees Celsius).

(B) All piping, fittings and valves other than the boiler supply and return lines shall have a minimum pressure and temperature rating equal to or greater than the maximum expected pressure and temperature that may be reached.

(c) Hot Water Supply Boilers.

(1) Pressure relief valves.

(A) Each hot water supply boiler shall have at least one pressure relief valve, of the automatic reseating type, identified with the ASME certification mark with the "V" or "HV" designators, and set to relieve at or below the MAWP of the boiler.

(B) When more than one pressure relief valve is used on a hot water supply boiler, the additional valve or valves shall be officially rated and may have a set pressure within a range not to exceed 6 psig (42 kilopascals) above the MAWP of the boiler up to and including 60 psig (414 kilopascals), and 5.0% for those having a MAWP exceeding 60 psig (414 kilopascals).

(C) Pressure relief valves shall be spring loaded. Pressure relief valves shall be set and sealed so that they cannot be reset without breaking the seal. A body drain connection below seat level shall be provided. For valves exceeding 2 1/2 inch nominal pipe size (65 mm), the drain hole or holes shall be tapped not less than 3/8 inch nominal pipe size (10 mm). For valves of 2 1/2 inch nominal pipe size (65 mm) or less, the drain hole shall not be less than 1/4 inch (6 mm) diameter.

(D) Each pressure relief valve shall have a substantial lifting device which will positively lift the disk from its seat at least 1/16 inch (1.6 mm) when there is no pressure on the boiler.

(E) Seats and disks of pressure relief valves shall be made of a suitable material to resist corrosion. No materials likely to fail due to deterioration or vulcanization, when subjected to saturated steam temperature corresponding to capacity test pressure, shall be used for any part.

(F) No pressure relief valve shall be smaller than 3/4 inch nominal pipe size (20 mm) nor larger than 4 1/2 inch nominal pipe size (115 mm) except that boilers having a heat input not greater than 15,000 Btu/hr (4.4 kilowatts) may be equipped with a rated pressure relief valve of 1/2 inch nominal pipe size (15 mm). The inlet opening shall have an inside diameter approximately equal to, or greater than, the seat diameter. In no case shall the minimum opening through any part of the valve be less than 1/4 inch (6 mm) diameter or its equivalent area.

(G) The required steam relieving capacity, in pounds per hour, of the pressure relieving device or devices on a boiler shall be the greater of that determined by dividing the maximum output in Btu at the boiler nozzle obtained by the firing of any fuel for which the unit is installed by 1,000, or shall be determined on the basis of pounds of steam generated per hour per square foot of boiler heating surface as given in §65.615, Exhibit 7. For cast iron boilers, the minimum valve capacity shall be determined by the maximum output method.

(H) In every case, the pressure relief valve capacity for each boiler with a single pressure relief valve shall be such that, with the fuel burning equipment installed and operated at maximum capacity, the pressure cannot rise more than 10% above the MAWP. When more than one pressure relief valve is used, the overpressure shall be limited to 10% above the set pressure of the highest set valve.

(I) Pressure relief valve piping. No valve shall be placed between the pressure relief valve and the boiler nor on the discharge pipe between the pressure relief valve and the drain. When a discharge pipe is used, it shall be full size and fitted with an open drain to prevent water from lodging in the upper part of the pressure relief valve or in the discharge pipe. When an elbow is placed on the pressure relief valve discharge pipe, it shall be located close to the valve outlet. The discharge pipe shall be securely anchored and supported, independent of the valve. Mufflers shall not be used on hot water supply boilers.

(J) Pressure relief valves and safety valves shall be installed on the boiler with spindles positioned vertically. The opening or connection between the boiler and any pressure relief valve or safety valve shall have at least the area of the valve inlet.

(2) Makeup water connections.

(A) Makeup water or water treatment shall be introduced into a boiler through the return piping system or through an independent makeup water connection which does not discharge against parts of the boiler exposed to direct radiant heat from the fire. Makeup water or water treatment shall not be introduced through openings or connections provided for inspection or cleaning, pressure relief valve, pressure gage, or temperature gage.

(B) Makeup water pipe shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler or between the check valve and the piping system.

(3) Low-water fuel cutoffs and water feeding devices.

(A) All automatically fired hot water supply boilers shall have an automatic low-water fuel cutoff that has been designed for hot water service, and it shall be so located as to automatically cut off the fuel supply when the surface of the water falls to a level below the normal waterline established.

(B) The MAWP of all low water fuel cutoff and flow sensing devices shall be set at or above the boiler stamped MAWP.

(C) When low-water fuel cutoff and feedwater pump controls are combined in a single device, an additional separate low-water fuel cutoff shall be installed. The additional control shall be wired in series electrically with the existing low-water fuel cutoff.

(D) When a low-water fuel cutoff is housed in either the water column or a separate chamber it shall be provided with a blowdown pipe and valve not less than 3/4 inch nominal pipe size (20 mm). The arrangement shall be such that when the water column is blown down, the water level in it will be lowered sufficiently to activate the low-water fuel cutoff device.

(E) As there is no normal water line to be maintained in a hot water supply boiler, any location of the low-water fuel cutoff above the lowest safe water level established by the boiler manufacturer is satisfactory.

(F) All automatically fired hot water heating boilers, when installed in a forced circulation system and not under continuous attendance, shall be equipped in the manner described in this subsection. A coil-type boiler or a water-tube boiler requiring forced circulation to prevent overheating of the coils or tubes shall have a flow sensing device which is listed by a nationally recognized testing agency to prevent burner operation at a flow rate inadequate to protect the boiler unit against overheating.

(G) If a water feed device is utilized, it shall be constructed to prevent feedwater from entering the boiler through the water column or separate chamber of the low-water fuel cutoff.

(4) Pressure and Temperature gages.

(A) Each hot water supply boiler shall have a pressure or altitude gage connected to it or to its flow connection which cannot be shut off from the boiler except by a cock with tee or lever handle placed in a pipe near the gage. The handle of the cock shall be parallel to the pipe in which it is located when the cock is open.

(B) The scale on the dial of the pressure or altitude gage shall be graduated to not less than 1 1/2 nor more than 3 1/2 times the pressure at which the pressure relief valve is set. The gage shall be provided with effective stops for the indicating pointer at the zero point and at the maximum pressure point.

(C) Piping and tubing for pressure or altitude gage connections shall be of nonferrous metal when smaller than 1 inch nominal pipe size (25 mm).

(D) Each hot water supply boiler shall have a thermometer or temperature gage located and connected so that it shall be readable, and shall be located so that it shall at all times indicate the temperature of the water in the boiler at or near the outlet. If placed on the outlet piping, it must be located between the stop valve and the boiler.

(5) Stop valves.

(A) Stop valves shall be located at an accessible point in the supply and return pipe connections near the boiler nozzle of a single hot water supply boiler installation to permit draining the boiler without emptying the system.

(B) When the boiler is located above the system and can be drained without draining the system, stop valves may be eliminated.

(C) Type of stop valve. When stop valves over two inches in size are used, they shall be of the outside screw-and-yoke rising stem type or of such other type as to indicate at a distance whether it is closed or open by the position of its stem or other operating mechanism. The wheel may be carried either on the yoke or attached to the stem. If the valve is of the plug cock type, it shall be fitted with a slow opening mechanism and an indicating device and the plug shall be held in place by a guard or gland.

(6) Drain valve.

(A) Each hot water supply boiler shall have one or more drain connections, fitted with valves or cocks connecting to the lowest water containing spaces. The minimum size of the drain piping, valves, and cocks shall be 3/4 inch nominal pipe size (20 mm). The discharge piping shall be full size to the point of discharge. When the blowoff connection is located at the lowest water containing space, a separate drain connection is not required.

(B) Minimum pressure rating. The minimum pressure rating of valves and cocks used for blowoff or drain purposes shall be at least equal to the pressure stamped on the boiler, but in no case less than 30 psig (207 kilopascals). The temperature rating of such valves and cocks shall not be less than 250 degrees Fahrenheit (121 degrees Celsius).

(7) Provisions for thermal expansion.

(A) If a system is equipped with a check valve or pressure reducing valve in the cold water inlet line, consideration should be given to the installation of an airtight expansion tank or other suitable air cushion. Otherwise, due to the thermal expansion of the water, the pressure relief valve may lift periodically.

(B) If an expansion tank is provided, it shall be constructed in accordance with the ASME Code, Section VIII, Division 1 or Section X, and the pressure and temperature ratings of the tank shall be equal to or greater than the pressure and temperature ratings of the system pressure. Except for pre-pressurized tanks, which should be installed on the cold water side, provisions shall be made for draining the tank without emptying the system.

(C) If the expansion tank was originally equipped with a sight glass, the sight glass and sight glass valves shall be in working condition at all times, and the water level shall be maintained as per the manufacturer's recommendations.

(8) Piping, Fittings and Valves.

(A) All piping, fittings and valves on the boiler supply and return lines shall have a pressure rating equal to or greater than the MAWP of the boiler and a temperature rating of no less than 250 degrees Fahrenheit (121 degrees Celsius).

(B) All piping, fittings and valves other than the boiler supply and return lines shall have a minimum pressure and temperature rating equal to or greater than the maximum expected pressure and temperature that may be reached.

(d) Potable Water Heaters (ASME Code HLW).

(1) Pressure relief valves.

(A) Potable water heaters (tank type) shall have at least one officially rated temperature and pressure relief valve, or one officially rated pressure relief valve, set to relieve at or below the maximum allowable pressure of the heater. No pressure relief valve shall be smaller than 3/4 inch nominal pipe size (20 mm). The valve (s) shall be marked with the ASME Code Symbol "V" or "HV". At no time shall the temperature probe of the temperature and pressure relief valve be removed or modified.

(B) The pressure relief valve shall have a capacity equal to or exceeding the rated burner input of the heater. The relieving capacity for electric water heaters shall be 3,500 Btu/hr (1.0 kilowatts) per kilowatt of input.

(C) The ASME Btu rating on the valve shall be used to determine the relieving capacity.

(D) Pressure relief valves shall be connected directly to the heater within the top 6 inches of the tank.

(E) Pressure relief valves may be installed vertically or horizontally. The center line of the horizontal connection shall be no lower than 4 inches from the top of the shell.

(F) Pressure relief valves shall not be connected to an internal pipe in the heater, or to a cold water feed line connected to the heater.

(G) Pressure relief valve piping. No valve shall be placed between the pressure relief valve and the boiler nor on the discharge pipe between the pressure relief valve and the drain. When a discharge pipe is used, it shall be full size and fitted with an open drain to prevent water from lodging in the upper part of the pressure relief valve or in the discharge pipe. When an elbow is placed on the pressure relief valve discharge pipe, it shall be located close to the valve outlet. The discharge pipe shall be securely anchored and supported, independent of the valve. Mufflers shall not be used on potable water heaters.

(2) Water supply.

(A) Water supply shall be introduced into a water heater through an independent water supply connection. Water shall not be introduced through openings or connections provided for cleaning, pressure relief valves, drains, pressure gage or temperature gage.

(B) If the water supply pressure to a hot water heater exceeds 75% of the set pressure of the pressure relief valve, a pressure reducing valve is required.

(3) Flow sensing device.

(A) All automatically fired potable water heaters, when installed in a forced circulation system and not under continuous attendance, shall be equipped in the manner described in this subsection. A coil-type boiler or a water-tube boiler requiring forced circulation to prevent overheating of the coils or tubes shall have a flow sensing device which is listed by a nationally recognized testing agency to prevent burner operation at a flow rate inadequate to protect the boiler unit against overheating.

(B) The MAWP of all flow sensing devices shall be set at or above the boiler stamped MAWP.

(4) Gages.

(A) Temperature gages. Each hot water heater shall have a thermometer located and connected at or near the outlet that is readable. The thermometer shall at all times indicate the temperatures of the water in the hot water heater. If placed on the outlet piping, it must be located between the stop valve and the boiler.

(B) Pressure gages. Each hot water heater that is of the coil type or water tube shall have a pressure gage located as close to the boiler as possible that is graduated to not less than 1 1/2 or more than 3 1/2 times the pressure at which the pressure relief valve is set.

(5) Stop valves. Stop valves should be placed in the supply and discharge pipe connections of the hot water heater installation to permit draining the heater without emptying the system.

(6) Drain valves. Each hot water heater shall have a bottom drain pipe connection fitted with a valve or cock connected to the lowest water space practical. The minimum size bottom drain shall be 3/4 inch nominal pipe size (20 mm).

(7) Provisions for thermal expansion.

(A) If a system is equipped with a check valve or pressure reducing valve in the cold water inlet line, consideration should be given to the installation of an airtight expansion tank or other suitable air cushion. Otherwise, due to the thermal expansion of the water, the pressure relief valve may lift periodically.

(B) If an expansion tank is provided, it shall be constructed in accordance with the ASME Code, Section VIII, Division 1 or Section X, and the pressure and temperature ratings of the tank shall be equal to or greater than the pressure and temperature ratings of the system pressure.

(C) Except for pre-pressurized tanks, which should be installed on the cold water side, provisions shall be made for draining the tank without emptying the system.

(D) If the expansion tank was originally equipped with a sight glass, the sight glass and sight glass valves shall be in working condition at all times, and the water level shall be maintained as per the manufacturer's recommendations.

(8) Piping, Fittings and Valves.

(A) All piping, fittings and valves on the boiler supply and return lines shall have a pressure rating equal to or greater than the MAWP of the boiler and a temperature rating of no less than 210 degrees Fahrenheit (99 degrees Celsius).

(B) All piping, fittings and valves other than the boiler supply and return lines shall have a minimum pressure and temperature rating equal to or greater than the maximum expected pressure and temperature that may be reached.

Filed with the Office of the Secretary of State, on July 31, 2018.


Brian E. Francis
Executive Director
Texas Department of Licensing and Regulation