Gas information sheet 05: Stainless steel pipe for consumer piping
In Australia, stainless steel piping materials and fittings can be used for consumer piping. There are strict requirements presented in Standard AS/NZS 5601:2013 and ESV strongly recommends gasfitters makes themselves familiar with these requirements.
Stainless steel pipe is specified as consumer piping material for the food preparation industry and medical, hospital and laboratory industries.
Stainless steel pipe would be used for the following reasons:
- frequent industrial-type cleaning or sterilizing will occur
- low maintenance piping material is required
- the location requires aesthetically pleasing piping material
- other material would be unsuitable.
Stainless steel pipe
There are two types of stainless steel pipe permitted to be used as consumer piping, each having specific uses and restrictions. They are:
- stainless steel pipe grade 316 (rigid)
- corrugated semi-rigid stainless steel pipe.
Stainless steel pipe, rigid or semi-rigid is not permitted beneath a building if in the ground or embedded in concrete unless it is plastic coated or covered with a proprietary coating acceptable to the Technical Regulator.
Further, where stainless steel consumer piping is to be embedded in a concrete wall or floor, the following shall apply:
- the operating pressure shall not exceed 7 kPa
- piping shall be placed so that cutting, bending or displacement of any reinforcement from its proper location is not necessary
- piping in a floor shall be placed between the top and bottom reinforcement
- the size of piping shall not reduce the design strength of the concrete slab
- piping shall not extend through expansion joints in the concrete.
Stainless steel pipe Grade 316 (rigid)
The maximum operating pressure for rigid stainless steel pipe shall not exceed 200 kPa.
Materials, dimensions and performance for this pipe must comply with AS 5200.053 and/or ASME B36.19 M.
Be aware stainless steel pipe may not be suitable in areas of high concentrations of chlorides such as a marine environment. Check with the pipe manufacturer if you are not sure the pipe is suitable for a marine environment. Pipe must be plastic coated for use beneath a building if in the ground or embedded in concrete. Make sure all joints and fittings are watertight and protected from damage.
Pipe fittings must be compatible with the pipe material used and the pipe manufacturer’s specifications. Press-fit end connectors must comply with AS 3688. Press-fit connectors shall not be used for applications where the operating temperature exceeds 70 oC unless otherwise specified by the manufacturer and must not be used as a final connection to an appliance where the final connection needs to be destroyed to disconnect the appliance.
Jointing beneath the ground should be kept to a minimum. Mechanical jointing shall have a minimum thickness of 1.2 mm. For welding stainless steel pipe a minimum wall thickness of 2.5 mm shall be used.
Field welding of stainless steel pipe requires special techniques. Only two welding methods for consumer piping are permitted by Energy Safe Victoria. These are:
- Tungsten inert Gas (TIG).
- Manual Metal Arc Welding (MMAW).
Filler metal for welding stainless steel pipe shall comply with AS/NZS 1167.2:1999 : Welding and brazing – Filler metals – Filler metal for welding.
Corrugated semi-rigid stainless steel pipe
The maximum operating pressure for semi-rigid corrugated stainless steel pipe shall not exceed 100 kPa.
Corrugated, semi-rigid pipe must comply with BS 7838. This type of pipe is not permitted to be used beneath a building unless plastic coated and without joints. Also corrugated, semi-rigid pipe must be plastic coated if it is to be embedded in a concrete wall or floor with an operating pressure not exceeding 7 kPa.
Plastic coated semi-rigid stainless steel piping shall not be used as an appliance connection. Final connections to appliances shall be made using copper pipe, steel pipe or a certified hose assembly unless, in the case of plastic coated semi-rigid stainless steel piping, it forms part of a certified hose assembly or limited flexibility connector.
Fittings are not permitted in the ground beneath a building.
Note: Where malleable cast iron fittings are used the operating limit is 7 kPa.
Mechanical jointing is permitted as long as components are in accordance with the manufacturer’s specifications. As with fittings, jointing is not permitted in the ground beneath a building.
Joints, in other locations, must be accessible for inspection and renewal. Joints must not be welded or jointed by any other method.
For further information contact the Gas Safety Information Line on 1800 652 563.