Standard Practice for Socket-Welding Reducer Inserts
1. Scope:
1.1 General Purpose:
- This Standard MSS SP-79 Practice aims to establish requirements for insert-type fittings, which, after being welded in place, effectively create a socket-welded reduced end fitting. These inserts include components like Tees, 90-degree Elbows (Ell), Crosses, 45-degree Elbows (Ell), Couplings, etc.
1.1.1 Fitting Sizes and Pipe Correlation:
- This Standard MSS SP-79 Practice primarily focuses on socket-welding reducer inserts designed for use with ASME B16.11 Class 3000 and 6000 socket-welding fittings.
- It provides dimensions, tolerances, finish, marking, and material requirements for these reducer inserts.
- Tables 3 and 3M present U.S. customary unit dimensions and SI (metric) dimensions, respectively.
- Table 1 in this standard lists the fittings covered, organized by class, size range, and their correlation to the schedule number or wall designation of pipes for rating calculations.
1.1.2 Partial Compliance Fittings:
- Specialized fittings with non-standard dimensions or those crafted from unconventional materials can be designed and manufactured through agreement between the manufacturer and the purchaser.
- These specialized fittings must be marked in accordance with the requirements outlined for partial compliance fittings in Section 5.1.1(e).
1.1.3 Welding Installation:
- The installation welding requirements are not the central focus of this Standard Practice. However, the standard provides the following exceptions:
- A CAUTIONARY NOTE REGARDING INSTALLATION OF SOCKET-WELDED JOINTS (refer to Section 12).
- Guidance on WELDING GAP AND MINIMUM SOCKET WALL THICKNESS (see Figure 1).
- GAP RECOMMENDATIONS (see Figure 2).
- Actual installation welding should align with the specific piping system into which the fittings will be integrated.
In summary, this Standard MSS SP-79 Practice establishes guidelines for socket-welding reducer inserts, facilitating the creation of socket-welded reduced end fittings. It addresses various aspects, including dimensions, tolerances, markings, materials, and their correlation with ASME B16.11 Class 3000 and 6000 socket-welding fittings. Additionally, it allows for customization and provides limited welding-related guidance.