Michigan Administrative Code › Department - Labor and Economic Opportunity › MIOSHA › General Industry and Construction Safety and Occupational Health Standards › General Industry Safety Standards › Part 12 - WELDING AND CUTTING › MANIFOLDING-SERVICE PIPING › Section R. 408.11242 - Piping assembly

Current through Vol. 24-12, July 15, 2024
Rule 1242.
(1)
						All piping shall be run as directly as practicable, shall be protected against
						physical damage, and proper allowance shall be made for expansion and
						contraction, jarring, and vibration. Piping in a tunnel, trench, or duct shall
						be welded or brazed. Pipe laid underground in earth shall be located below the
						frost line and shall be protected from corrosion. Shutoff valves shall be
						located outside the conduits. Oxygen piping may be placed in the same tunnel,
						trench, or duct with fuel gas pipe lines if natural or forced ventilation is
						provided.
(2) Low points in piping
						carrying moist gas shall be drained into drip pots constructed so as to permit
						pumping or draining out the condensate at necessary intervals. A drain valve
						shall be installed for this purpose, having an outlet normally closed with
						screw caps or plugs. Open end valves or petcocks shall not be used, except
						that, in drips located out of doors, underground, and not readily accessible, a
						valve may be used at such points if it is equipped with means to secure it in
						the closed position. A pipe leading to the surface of the ground shall be cased
						or jacketed where necessary to prevent loosening or breaking.
(3) A gas shutoff valve shall be provided at
						the pipe entrance to a building. There shall also be provided a shutoff valve
						in the discharge line from the generator, gas holder, manifold, or other source
						of supply. A shutoff valve shall not be installed in a manner that renders a
						safety relief device ineffective.
(4) Before assembly, piping and fittings
						shall be freed of scale and dirt. An oxygen line shall be washed out with a
						solution such as caustic soda or trisodium phosphate. After assembly, piping
						shall be blown out with oil-free air or oil-free inert gas.
(5) Loose dirt that may have been trapped in
						the pipe shall be blown out with oil-free air or oil-free inert gas.
(6) Pressure testing of a pipeline shall be
						done in a manner to protect an employee from injury due to blowing out of
						closures and other pressure restraining devices.
(7) A piping system shall be tested and
						proved gastight at 1 1/2 times the maximum operating pressure and shall be
						purged of air before being placed in service. The material used for testing
						oxygen lines shall be oil-free and noncombustible. A flame shall not be used to
						detect leaks.
(8) Repairs on
						ferrous piping for other than inert gas lines shall be preceded by purging the
						lines, unless only nonsparking tools are used. When gas lines and other parts
						of a manifold system are being purged, a source of ignition shall not be
						permitted near the uncapped opening.
(9) Outdoor ferrous and all underground
						piping and fittings shall be covered or painted to protect against
						corrosion.
(10) A steel or wrought
						iron pipe joint shall be welded, threaded, or flanged.
(11) A brass or copper pipe joint shall be
						welded, brazed, threaded, or flanged. A seamless copper, brass, or stainless
						steel tubing joint shall be brazed or gas tubing fittings used. Where a
						socket-type joint is used, it shall be brazed with silver brazing alloy or
						similar filler metal having a melting point not less than 800 degrees
						Fahrenheit.