PIPES, TUBES, AND FITTINGS
This section covers the selection, application, and installation of pipe, tubes, and fittings commonly used for heating, air-conditioning, and refrigeration. Including, pipe hangers and pipe expansion
When selecting and applying these components, we must follow applicable local codes, state or provincial codes, and voluntary industry standards.
PIPES, TUBES, AND FITTINGS in United States Codes and Standards
The following organizations in the United States issue codes and standards for piping systems and components:
ASME — American Society of Mechanical Engineers
ASTM — American Society for Testing and Materials
NFPA — National Fire Protection Association
BOCA — Building Officials and Code Administrators,
MSS — Manufacturers Standardization Society of the
Valve and Fittings Industry, Inc.
AWWA — American Water Works Association
PIPES TUBES AND FITTINGS Steel Pipe Making Processes
We use several processes to make steel pipe. Seamless pipe, made by piercing or extruding, has no longitudinal seam. Other manufacturing methods roll a strip or sheet of steel (skelp) into a cylinder and weld a longitudinal seam. A continuous-weld (CW) furnace butt-welding process forces and joins the edges together at high temperature. An electric current welds the seam in electric resistance welded (ERW) pipe. ASTM Standards A106 and A53 specify steel pipe. Both standards specify A and B grades. The A grade has a lower tensile strength and is less popular.
Copper and its Alloy
We often use copper and copper alloys in HVAC and water supply because of their inherent resistance to corrosion and ease of installation. Moreover, there are two principal classes of copper tube. ASTM Standard B88 includes Types K, L, M, and DWV for water and drain service. ASTM Standard B280 specifies air-conditioning and refrigeration (ACR) tube for refrigeration service.
Cast and Ductile Iron
Cast-iron soil pipe comes in XH or service weight. We don’t use it under pressure because the pipe is not suitable and the joints is not good. Cast-iron pipe and fittings typically have bell and spigot
ends for lead and oakum joints or elastomer push-on joints. Cast-iron pipe and fittings are also furnished with no-hub ends for joining with no-hub clamps. Local plumbing codes specify permitted materials
and joints. Ductile iron has now replaced cast iron for pressure pipe. Moreover, ductile iron is stronger, less brittle, and similar to cast iron in corrosion resistance. Hence, it is commonly for buried pressure water mains or in other locations where internal or external corrosion is a problem. Joints are made with flanged fittings, mechanical joint (MJ) fittings, or elastomer gaskets for bell and spigot ends. Bell and spigot and MJ joints are not self-restrained. However, restrained MJ systems are available. Ductile-iron pipe is made in seven thickness classes for different service conditions. AWWA Standard C150/A2l.50, Thickness Design
of Ductile-Iron Pipe, covers the proper selection of pipe classes.