512 EM 385-1-1 Chapters 16-22

20-8. General Requirements.

General Pressurized Equipment and Systems

Designated personnel must tag unsafe pressurized equipment as "UNSAFE PRESSURIZED SYSTEM - DO NOT USE" and locate the tag at the controls.
Operators and maintainers must adhere to design pressure limits and not remove or disable safety devices except for immediate repairs, using proper LOTO procedures.
Install pressure gauges, safety, and relief valves on all pressurized systems, ensuring they comply with set standards and are maintained in good condition.

Compressed Air and Gas Systems

Construct, install, and maintain air receivers, safety valves, and related equipment according to ASME standards, ensuring safe operating pressures are not exceeded.
Ensure safe access to compressors and related equipment for operation, maintenance, and repair, and guard against hazards from discharge and high-pressure hose connections.
Do not use compressed air for cleaning purposes unless the outlet pressure is regulated to less than 30 psi (206.8 kPa) and then only when effective chip guarding and PPE (for example, face shield and safety glasses) are in place. This 30 psi (206.8 kPa) requirement does not apply to concrete form, mill scale, and similar cleaning purposes.

Air Receivers and Piping

Install air receivers and piping to allow for drainage, external inspection, and to minimize condensation and oil pockets.
Equip air receivers with drain valves and automatic traps, draining them regularly to prevent excessive liquid accumulation.
Ensure proper installation and maintenance of stop valves, safety valves, and all connections in compliance with manufacturer's instructions and standards.

Knowledge Check Choose the best answer for the question.

20-4. Do not use compressed air for cleaning purposes unless the outlet pressure is regulated to _____.

15 psi of less

15 to 30 psi

less than 30 psi

30 to 45 psi

You forgot to answer the question!

EM 385-1-1 Paragraph 20-8 (a.–b.).

20-8. General Requirements. (a.–b.).

a.  General. (20-8.a)

(1)  Tag any pressurized equipment or system found to be in an unsafe operating condition as "UNSAFE PRESSURIZED SYSTEM - DO NOT USE". Locate the tag at the controls. Do not use the equipment until the unsafe conditions are corrected.

(2)  Only designated personnel may operate or maintain pressurized equipment and systems.

(3)  Do not operate any pressurized equipment or systems above their design pressure.

(4)  Do not remove or make ineffective any safety appliance or device, except for when making immediate repairs or adjustments.  Ensure that the pressure is relieved and the power shut off using proper LOTO procedures prior to working on the equipment or systems. (See chapter 12).

(5)  Prepare a written safe clearance (that is, control of hazardous energy) procedure prior to repairing or adjusting equipment or systems under pressure (see chapter 12).

(6)  Locate discharge from safety valves, relief valves, and blowoffs so that it is not a hazard to personnel.

(7)  Master valves and controls must be either located or equipped to permit operation from the floor level, or they must be provided with safe access to them.

(8)  Provide a pressure gauge on all pressurized equipment and systems; and maintain it in good operational condition.

(9)  Provide safety and relief valves on all pressurized equipment and systems.

(a)  Do not set the safety relief valve higher than the maximum allowable pressure of the receiver or the system.  A safety relief valve setting not more than 10% over working pressure is recommended.

(b)  Do not place valves between the pressure vessel or generating equipment and a safety or relief valve, or between the safety or relief valve and the atmosphere, unless the configuration meets the requirements of the ASME BPVC.

(c)  Only qualified mechanics using appropriate equipment may adjust or change the settings of safety relief valves (see para 20-3.b).  All valves must be sealed after adjusting.

(d)  Check the functioning of the pressure gauge immediately if the pressure
        gauge registers above the maximum allowable working pressure and the safety or relief valve does not open. If the safety or relief valve is inoperative or malfunctioning, then remove the associated equipment from service until the safety or relief valve is adjusted or replaced.

(10)  Piping must meet requirements of the ASME B31.

(11) Provide an automatic shut-off or other enabling device control on pressurized manual equipment that might whip or rotate if released.

(12) Except where automatic shutoff valves are used, install safety lashings or suitable double action locking devices where high-pressure hose lines connect to machines or another high-pressure line.

(13) Secure the connections to high pressure hoses with a safety lashing or whip check.

(a)  Safety lashings must be made of two metal hose clamps connected by a flexible lacing.  The metal hose clamps must attach to the hose ends separate from the quick makeup connection.

(b)  The flexible lacing material must be suitably strong material.  Wires or pins through the quick makeup connection are not acceptable for use as safety lashings.

(14) Equip all pressurized cylinders, actuating booms, outriggers, or other load supporting appliances with pilot check valves, holding valves, or positive mechanical locks to prevent movement in case of failure in the pressure system.  Pressure system fitting replacement parts must be equivalent to the manufacturer's standards.

b.  Compressed Air and Gas Systems.  (20-8.b)

(1)  Construct air receivers according to the ASME BPVC.

(2)  Construct, install, test, and maintain all safety valves according to the ASME BVPC.

(3)  Access and Guarding.

(a)  Locate compressors and related equipment to allow safe access to all parts of the equipment for operation, maintenance, and repairs.

(b)  Construct, locate, and install safety appliances, such as valves, indicating devices, and controlling devices, so that they cannot be readily rendered inoperative by any means, including the elements.

(4)  Do not exceed the manufacturer’s safe operating pressure for air hoses, pipes, filters, or valves and other fittings.  Remove defective hoses from service.

(5)  To avoid tripping hazards, do not lay hoses over ladders, steps, scaffolds, or walkways.

(6)  Do not use compressed air to blow dirt from the hands face or clothing.

(7)  Do not use compressed air for cleaning purposes unless the outlet pressure is regulated to less than 30 psi (206.8 kPa) and then only when effective chip guarding and PPE (for example, face shield and safety glasses) are in place.  This 30 psi (206.8 kPa) requirement does not apply to concrete form, mill scale, and similar cleaning purposes.

(8)  When used with tools and equipment such as track drills, all airlines exceeding one-half (½) inch (1.3 cm) inside diameter must have a safety device at the source of supply or branch line to reduce pressure in case of hose failure.

(9)  Governors.

(a)  Install a speed governor, independent of the unloaders, on all air compressors, except those driven by electrical induction or electrical synchronized motors.

(b)  If the air compressor is engine or turbine driven, install an auxiliary control to the governor to prevent racing when the unloader operates.

(10) Every air compressor must automatically stop its air compression operation before the discharge pressure exceeds the maximum working pressure allowable on the weakest portion of the system.

(a)  If this automatic mechanism is electrically operated, the actuating device must be designed and constructed so that the electrical contact or contacts cannot lock or fuse in a position that will cause the compressor to continue its operation.

(b)  An air bypass and alarm may be used as an alternative.

(11) Make provisions to exclude flammable materials and toxic gases, vapors, or dusts from the compressor and compressor intake and to prevent steam, water, or waste being blown or drawn into a compressor intake.

(12) Do not install valves in the air intake pipe to an air compressor with an atmospheric intake.

(13) The air discharge piping from the compressor to the air receiver must be at least as large as the discharge opening on the air compressor.

(14) Install a stop valve between the air receiver and each piece of stationary utilization equipment at a point convenient to the operator.  Additionally, install a stop valve at each outlet to which an air hose may be attached.

(15) If a stop valve is located between the compressor and the receiver, install spring-loaded safety valves between the air compressor and the stop valve.

(a)  Safety valves must be capable of limiting pressure in the air discharge piping to 10% above the working pressure of the piping.

(b)  Stop valves should be the gate type.  If a globe valve is used, it must be installed so that the pressure is under the seat and that the valve will not trap condensation.

(16) Make provisions in compressed air and gas systems for expansion and contraction and to counteract pulsation and vibration.

(17)  Equip piping with traps or other means for removing liquid from the lines.

(18)  Install air discharge piping to eliminate possible oil pockets.

(19)  Installation and location of air receivers.

(a)  Install air receivers so that all drains, hand holes, and manholes are accessible.

(b)  Support air receivers with sufficient clearance to permit a complete external inspection and to avoid corrosion of external surfaces.

(d)  Locate the receiver to keep the discharge pipe as short as possible.

(e)  Locate the receiver in a cool place to facilitate condensation of moisture and oil vapors.

(20) Install a drain valve at the lowest point of every air receiver for the removal of accumulated oil and water.

(21)  Automatic traps may be installed in addition to drain valves.

(22) Open the drain valve on the air receiver and drain the receiver often enough to prevent the accumulation of excessive liquid in the receiver.

(23) Do not change tools or repair work until the stop valve in the air line supplying the equipment is closed.

(24) Use soapy water or any suitable non-toxic, non-flammable solution to clean the system.

(25) Use hose and hose connections used for connecting compressed air to utilization equipment that are designed for the pressure and service to which they are subjected according to the manufacturer’s instructions.