After three years of development, the first stage of a Standard covering the grade and dimensions of stainless steel pipes and tubes suitable for water supply and drainage systems has been completed. This interim Standard will be converted to a full Australian Standard in 2009.
The Standards Committee included ASSDA representative Neil McPherson of OneSteel, supported by the Technical Committee.
To avoid possible confusion and protect against corrosion problems in aggressive water supply areas, grades 316 and 316L are specified for the plumbing installation Code of Practice. All materials that satisfy the requirement for water supply and drainage systems must be included in the installation Standard AS/NZS 3500 Parts 1 & 2, which covers the material, grade and approved jointing method for piping systems.
If a material is included in Part 1 Water Supply (for drinking water), it will need to be certified against a product standard to Level 1, while Part 2 Drainage & Sanitary Plumbing requires Level 2 certification. The main difference is that Level 1 products require testing under AS4020 Material in Contact with Drinking Water to confirm lack of water contamination. Stainless steel product readily passes this testing.
All fittings, including the mechanical jointed pressfit and roll grooved types used for the plumbing services, are also tested and certified. AS3688 Metallic End Connectors defines the criteria against which these fittings are certified, including the additional pressure and fatigue testing to demonstrate strength of joint assembly.
Stainless steel using mechanical jointing systems
Mild steel, copper tube and plastic pipes have dominated building water systems for many years. However, high rise developments over recent decades have changed the building industry requirements for water supply and fire protection systems. These systems now require materials with a much higher pressure rating and corrosion resistance.
Stainless steel is recognised as a material most suited to meet these requirements. However, older on-site methods for jointing and fabrication has limited the use of stainless steel.
The approval of mechanical pressfit and roll grooved systems for all water systems has provided a major market for stainless. Stainless steel pipes and fittings have been installed as a solution to specific technical issues including a corrosive environment, high pressure requirements of the hydraulic services system, high operating temperature, or where the project owners are looking for a whole-of-life sustainable product solution.
The following projects illustrate some design and installation specifications around Australia.
Casey Aged Care Facility, Heidelberg, Victoria
108mm and 76mm tube in 316L was supplied by Blucher for a low pressure system feeding rainwater from storage tanks to pumps. Stainless steel was chosen due to concern of longevity and water contamination from other materials due to water levels in storage tanks being low or empty for long periods during dry spells. The Mapress stainless steel pressfitting system was familiar to the plumbing contractor who felt it was labour saving and easy to install. Plastic pipes were used from the roof to the plastic rainwater storage tanks.
Western Corridor Recycled Water Project, SE Queensland
The Mapress 316 pressure system was chosen for rapid, simple installation. There was a lack of pipe fitters available so socket welding was not possible and other trades made the installation. Sizes ranged from 15 to 54mm with butyl rubber sealing rings containing pressures up to 1,000kPa. The stainless steel was used for potable, treated and fire water as well as compressed air. The Mapress system supplied by Blucher has been used in all three waste water treatment plants in the Western Corridor as well as in the Gold Coast Desalination Plant.
Centre Court Business Park, North Ryde, NSW
Heating and chilled/condenser water installations used 316L schedule 5 pipe in both 50 and 100mm diameter in this 30,000m2 low rise complex. Stainless steel offered reliable protection from corrosion and the Victaulic roll grooved system offered ease of assembly.
Suncorp building, Sydney CBD
Refurbishment of the combined fire and drinking water system in a 1972 building used OneSteel Building Services supplied 316L schedule 10 pipe and fittings in 3m, pre grooved lengths for assembly in restricted duct spaces. The 43 floors plus 3 basements ensured high pressure requiring strong stainless steel which also met the drinking water AS4020 requirements.
Centrepoint Tower, Sydney CBD
Stainless steel pipe and fittings were supplied by OneSteel Building Services to replace corroded carbon steel in the 305m tall tower. Systems changed were the fire and potable water and the gas lines. 300m of 316L was supplied in 2.7m lengths which were roll grooved and assembled using Victaulic couplings in a very constricted service duct. Sizes used were 100mm and 50mm in schedule 10 except for gas lines in schedule 40.
This article featured in Australian Stainless magazine - Issue 45, Summer 2009.