South Carolina Code of Regulations
Chapter 71 - DEPARTMENT OF LABOR, LICENSING AND REGULATION-DIVISION OF LABOR
Article 9 - BOILER SAFETY PROGRAM
Subarticle 3 - EXISTING INSTALLATION
Section 71-9103.2 - Heating Boilers

Universal Citation: SC Code Regs 71-9103.2

Current through Register Vol. 48, No. 9, September 27, 2024

A. EHB-1 Standard Boilers

The maximum allowable working pressure of standard boilers shall in no case exceed the pressure indicated by the manufacturer's identification stamped or cast on the boiler or on a plate secured to it.

B. EHB-2 Nonstandard Riveted Boilers

The maximum allowable working pressure on the shell of a nonstandard riveted heating boiler shall be determined in accordance with EB0-3 of 71-9103.1. (C), except that in no case shall the maximum allowable working pressure of a steam-heating boiler exceed 15 psig, or a hot water boiler exceed 160 psig or 250°F temperature.

C. EHB-3 Nonstandard Welded Boilers

The maximum allowable working pressure of a nonstandard steel or wrought iron heating boiler of welded construction shall not exceed 15 psig for steam. For other than steam service, the maximum allowable working pressure shall be calculated in accordance with Section IV of the ASME Code, but in no case shall it exceed 30 psig.

D. EHB-4 Nonstandard Cast-Iron Boilers

1. The maximum allowable working pressure of a nonstandard boiler composed principally of cast iron shall not exceed 15 psig for steam service or 30 psig for hot water service.

2. The maximum allowable working pressure of a nonstandard boiler having cast-iron shell or heads and steel or wrought-iron tubes shall not exceed 15 psig for steam service or 30 psig for hot water service.

E. EHB-5 Potable Water Heaters

A potable water heater shall not be installed or used at pressures exceeding 160 psig or water temperatures exceeding 210°F.

F. EHB-6 Safety Valves

1. Each steam boiler shall have one or more ASME/National Board-stamped and certified safety valves of the spring pop-type adjusted and sealed to discharge at a pressure not to exceed 15 psig. Seals shall be attached in a manner to prevent the valve from being disassembled without breaking the seal. The safety valves shall be arranged so that they cannot be reset to relieve at a higher pressure than the maximum allowable working pressure on the boiler. The manufacturer shall provide a body drain connection below seat level and this drain shall not be plugged during or after field inspection. For valves exceeding 2-1/2 in. pipe size, the drain hole or holes shall be tapped not less than 3/8 in. pipe size. For valves 2-1/2 in. in pipe size and smaller, the drain hole shall not be less than 1/4 in. in diameter.

2. No safety valve for a steam boiler shall be smaller than 1/2 in. No safety valve shall be larger than 4-1/2 in. The inlet opening shall have an inside diameter equal to, or greater than, the seat diameter.

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

4. 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 Table EHB-6. In many cases a greater relieving capacity of valves than the minimum specified by these rules will have to be provided. In every case, the requirements of EHB-6(5) shall be met.

TABLE EHB-6

Minimum Pounds of Steam Per Hour Per Square Foot of Heating Surface

Fire tube Boilers

Water tube Boilers

Boiler Heating Surface:

Hand-fired

5

6

Stoker-fired

7

8

Oil, gas, or pulverized fuel-fired

8

10

Water wall Heating Surface:

Hand-fired

8

8

Stoker-fired

10

12

Oil, gas, or pulverized fuel-fired

14

16
a. When a boiler is gas fed and does not have a heat value in excess of 200 BTU per cu. ft., the minimum safety valve or safety relief valve relieving capacity may be based on the value given for hand fed boilers above.

b. The minimum safety valve or safety relief valve relieving capacity for electric boilers shall be 3-1/2 pounds per hour per kilowatt input.

c. For heating surface determination see ASME Code Section IV, Paragraph HG-403.

5. The safety valve capacity for each steam boiler shall be such that with the fuel burning equipment installed and operating at maximum capacity, the pressure cannot rise more than 5 psig above the maximum allowable working pressure.

6. When operating conditions are changed, or additional boiler heating surface is installed, the valve capacity shall be increased, if necessary, to meet the new conditions and be in accordance with EHB-6(5). When additional valves are required, they may be installed on the outlet piping provided there is no intervening valve.

7. If there is any doubt as to the capacity of the safety valve, an accumulation test shall be run (See ASME Code, Section VI, Recommended Rules for Care and Operation of Heating Boilers).

8. No valve of any description shall be placed between the safety valve and the boiler, or on the discharge pipe between the safety valve and the atmosphere. The discharge pipe shall be at least full size and be fitted with an open drain to prevent water lodging in the upper part of the safety valve or in the discharge pipe. When an elbow is placed on the safety valve discharge pipe, it shall be located close to the safety valve outlet or the discharge pipe shall be securely anchored and supported. All safety valve discharges shall be so located or piped as not to endanger persons working in the area.

G. EHB-7 Safety Relief Valve Requirements for Hot Water Heating and Hot Water Supply Boilers

1. Each hot water heating and hot water supply boiler shall have at least one ASME/National Board-stamped and certified safety relief valve set to relieve at or below the maximum allowable working pressure of the boiler. Each hot water supply boiler shall have at least one ASME-National Board-stamped and certified safety relief valve of the automatic reseating type set to relieve at or below maximum allowable working pressure of the boiler. Safety relief valves ASME-National Board-stamped and certified as to capacity shall have pop action when tested by steam. When more than one safety relief valve is used on either a hot water heating or hot water supply boiler, the additional valve or valves shall be ASME National Board-stamped and certified and may be set within a range not to exceed 6 psig above the maximum allowable working pressure of the boiler up to and including 60 psig and 5 percent for those having a maximum allowable working pressure exceeding 60 psig. Safety relief valves shall be spring-loaded. Safety relief valves shall be so arranged that they cannot be reset at a higher pressure than the maximum permitted by this paragraph.

2. No materials liable to fail due to deterioration or vulcanization when subject to saturated steam temperature corresponding to capacity test pressure shall be used for any part.

3. No safety relief valve shall be smaller than 3/4 in. nor larger than 4-1/2 in. standard pipe size, except that boilers having a heat input not greater than 15,000 BTU per hour may be equipped with a safety relief valve of 1/2 in. standard pipe size. 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 in. in diameter or its equivalent area.

4. 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 Table EHB-6. In many cases, a greater relieving capacity of valves will have to be provided than the minimum specified by these rules. In every case, the requirements of EHB-7(6) shall be met.

5. When operating conditions are changed, or additional boiler heating surface is installed, the valve capacity shall be increased, if necessary, to meet the new conditions and shall be in accordance with EHB-7(6). The additional valves required, on account of changed conditions, may be installed on the outlet piping provided there is no intervening valve.

6. Safety relief valve capacity for each boiler shall be such that, with the fuel burning equipment installed and operated at maximum capacity, the pressure cannot rise more than 10 percent above the maximum allowable working pressure. When more than one safety relief valve is used, the over-pressure shall be limited to 10 percent above the set pressure of the highest set valve allowed by EHB-6(1).

7. If there is any doubt as to the capacity of the safety relief valve, an accumulation test shall be run (See ASME Code, Section VI, Recommended Rules for Care and Operation of Heating Boilers).

8. No valve of any description shall be placed between the safety relief valve and the boiler, or on the discharge pipe between the safety relief valve and the atmosphere. The discharge pipe shall be not less than the diameter of the safety relief valve outlet and fitted with an open drain to prevent water lodging in the upper part of the safety relief valve or in the discharge pipe. When an elbow is placed on the safety relief valve discharge pipe, it shall be located close to the safety relief valve outlet, or the discharge pipe shall be securely anchored and supported. All safety relief valve discharges shall be so located or piped as not to endanger persons working in the area.

H. EHB-8 Steam Gauges

1. Each steam boiler shall have a steam gauge or a compound steam gauge connected to its steam space or to its water column or to its steam connection. The gauge or connection shall contain a siphon or equivalent device which will develop and maintain a water seal that will prevent steam from entering the gauge tube. The connection shall be so arranged that the gauge cannot be shut off from the boiler except by a cock placed in the pipe at the gauge and provided with a tee or lever handle arranged to be parallel to the pipe in which it is located when the cock is open. The connections to the boiler shall be not less than 1/4 in. standard pipe size, but where steel or wrought-iron pipe or tubing is used, they shall be not less than 1/2 in. standard pipe size. The minimum size of a siphon, if used, shall be 1/4 in. inside diameter. Ferrous and nonferrous tubing having inside diameters at least equal to that of standard pipe sizes listed above may be substituted for pipe.

2. The scale on the dial of a steam boiler gauge shall be graduated to not less than 30 psig nor more than 60 psig. The travel of the pointer from 0 to 30 psig pressure shall be at least 3 in.

I. EHB-9 Pressure or Altitude Gauges and Thermometers

1. Each hot water boiler shall have a pressure or altitude gauge connected to it or to its flow connection in such a manner that it cannot be shut off from the boiler except by a cock with tee or lever handle, placed on the pipe near the gauge. The handle of the cock shall be parallel to the pipe in which it is located when the cock is open.

2. The scale on the dial of the pressure or altitude gauge shall be graduated approximately to not less than 1-1/2 nor more than three times the pressure at which the safety relief valve is set.

3. Piping or tubing for pressure or altitude-gauge connections shall be of nonferrous metal when smaller than 1 in. pipe size.

4. Each hot water boiler shall have a thermometer so located and connected that it shall be easily readable when observing the water pressure or altitude. The thermometer shall be so located that it shall at all times indicate the temperature in degrees Fahrenheit of the water in the boiler at or near the outlet.

J. EHB-10 Water Gauge Glasses

1. Each steam boiler shall have one or more water gauge glasses attached to the water column or boiler by means of valved fittings not less than 1/2 in. pipe size, with the lower fitting provided with a drain valve of a type having an unrestricted drain opening not less than 1/4 in. in diameter to facilitate cleaning. Gauge glass replacement shall be possible under pressure. Water glass fittings may be attached directly to a boiler.

2. Boilers having an internal vertical height of less than 10 in. may be equipped with a water level indicator of the glass bull's-eye type provided the indicator is of sufficient size to show the water at both normal operating and low-water cutoff levels.

3. The lowest visible part of the water gauge glass shall be at least 1 in. above the lowest permissible water level recommended by the boiler manufacturer. With the boiler operating at this lowest permissible water level, there shall be no danger of overheating any part of the boiler.

4. Each boiler shall be provided at the time of manufacture with a permanent marker indicating the lowest permissible water level. The marker shall be stamped, etched, or cast in metal; or it shall be a metallic plate attached by rivets, screws, or welding; or it shall consist of material with documented tests showing its suitability as a permanent marking for the application. This marker shall be visible at all times. Where the boiler is shipped with a jacket, this marker may be located on the jacket.

5. In electric boilers of the submerged electrode type, the water gauge glass shall be so located to indicate the water levels both at startup and under maximum steam load conditions as established by the manufacturer.

6. In electric boilers of the resistance heating element type, the lowest visible part of the water gauge glass shall not be below the top of the electric resistance-heating element. Each boiler of this type shall also be equipped with an automatic low-water electrical power cutoff so located as to automatically cut off the power supply before the surface of the water falls below the top of the electrical resistance heating elements.

7. Tubular water glasses on electric boilers having a normal water content not exceeding 100 gal. shall be equipped with a protective shield.

K. EHB-11 Stop Valves

1. When a stop valve is used in the supply pipe connection of a single steam boiler, there shall be one used in the return pipe connection.

2. Stop valves in single hot water heating boilers shall be located at an accessible point in the supply and return pipe connections, as near the boiler nozzle as is convenient and practicable, to permit draining the boiler without emptying the system.

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

4. A stop valve shall be used in each supply and return pipe connection of two or more boilers connected to a common system.

5. All valves or cocks shall conform to the applicable portions of HF-203 of Section IV of the ASME Code and may be ferrous or nonferrous.

6. The minimum pressure rating of all valves or cocks shall be at least equal to the pressure stamped upon the boiler, and the temperature rating of such valves or cocks, including all internal components, shall be not less than 250°F.

7. Valves or cocks shall be flanged, threaded or have ends suitable for welding or brazing.

8. All valves or cocks with stems or spindles shall have adjustable pressure-type packing glands and, in addition, all plug-type cocks shall be equipped with a guard or gland. The plug or other operating mechanism shall be distinctly marked in line with the passage to indicate whether it is opened or closed.

9. All valves or cocks shall have tight closure when under boiler pressure test.

10. When stop valves are used, tags of metal or other durable material fastened to them shall properly designate them substantially.

L. EHB-12 Feed Water Connections

1. Feed water, makeup water, or water treatment shall be introduced into a boiler through the return piping system. Alternatively, makeup water or water treatment may be introduced through an independent connection. The water flow from the independent connection shall not discharge directly 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, safety valve, safety relief valve, blow off, water column, water gauge glass, pressure gauge, or temperature gauge.

2. The 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 return pipe system.

M. EHB-13 Water Column and Water Level Control Pipes

1. The minimum size of ferrous or nonferrous pipes connecting a water column to a steam boiler shall be 1 in. No outlet connections, except for damper regulator, feed water regulator, steam gauges, or apparatus which does not permit the escape of any steam or water except for manually operated blow downs, shall be attached to a water column or the piping connecting a water column to a boiler (see HG-705 of Section IV of the ASME Code for introduction of feed water into a boiler). If the water column, gauge glass, low-water fuel cutoff, or other water level control device is connected to the boiler by pipe and fittings, no shutoff valves of any type shall be placed in such pipe, and a cross or equivalent fitting to which a drain valve and piping may be attached shall be placed in the water piping connection at every right-angle turn to facilitate cleaning. The water column drainpipe and valve shall be not less than 3/4 in. pipe size.

2. The steam connections to the water column of a horizontal fire tube wrought-iron boiler shall be taken from the top of the shell or the upper part of the head, and the water connection shall be taken from a point not above the centerline of the shell. For a cast-iron boiler, the steam connection to the water column shall be taken from the top of an end section or the top of the steam header, and the water connection shall be made on an end section not less than 6 in. below the bottom connection to the water gauge glass.

N. EHB-14 Return Pump

Each boiler equipped with a condensate return pump shall be provided with a water level control arranged to automatically maintain the water level in the boiler within the range of the gauge glass.

O. EHB-15 Repairs and Renewals of Fittings and Appliances

Whenever repairs are made to fittings or appliances, or it becomes necessary to replace them, the repairs must comply with Section IV of the ASME Code for new construction.

Disclaimer: These regulations may not be the most recent version. South Carolina may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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