MSS SP-83 Socket Welding and Threaded Steel Pipe Unions

1 .SCOPE

1.1 This Standard Practice establishes envelope and other essential dimensionals, finish, tolerances, testing, marking, material, and minimum performance requirements for forged carbon and stainless steel pipe unions, socket welding and threaded ends.

2 .PRESSURE RATINGS

2.1 These unions shall be designated as Class 3000 socket welding or threaded and shall carry ratings shown in Table 1.

TABLE 1 Pressure一emperature Service Rating

Class 3000 Carbon and Stainless Steel

Unions Socket Welding&Threaded Ends

4 .2 The seating surfaces of the joint will be steel to steel, ball to cone design . Male and Femaae ends shall be machined with sockets for socket welding or threaded with internal NPT pipe threads.Male and Female ends and Nuts may be round, polygon, or modified polygon with rounded corners, at the option of the manufacturer.The lenght of the union ends shall be sufficient to provide a suitable wrenching surface.

5 .MARKING

5.1 Each union Nut shall be permanently marked accordance with MSS SP-25 .The marking shall

include (but is not limited to) the following:

A)Manufacturer’s name or trademark.

B) Material grade identification in accordance with the requirements of the applicable ASTM specification listed in Section 6.

Note: Multiple material marking shall be allowed as covered in ASTM material specifications listed

in Section 6 .1.

c)Material lot or heat number for traceability.

d)Service designation:3000 or 3M (M to designate units pf 1000)

e)The nominal pipe size.

5.2 The Male and Female union ends shall be permanently marked with the following:

a)Manufacturer’s name or trademark.

b)Material grade identification.(See Section 5.1b)

c)Material lot or heat number for traceability.

5.3 All three parts of a union, in compliance with all requirements of this SP, shall be marked SP83.

6 .MATERIAL

6.1 The three parts of a union assembly shall be manufactured from materials which have the same requirements for chemical composition, mechanical properties, and applicable heat treatment, except that F304 and F316 union nuts may be used with F304L and F316L end pieces, respectively. Material specification ASTM A 182 applies for stainless steel, grades F3041 F304L / F316 / F316L Stainless steel austenitic unions are suitable for use with ASTM A312/A312M pipe.

Note:Multiple Material Marking:

Stainless Steel unions, me

eting the chemical and mechanical properties for more than one class or grade, may, at the manufacturer’s option, be marked with more than one class or grade designation, such as F304/304L and F316 /316L.

Material specification ASTM A 105 applies for carbon steel .Carbon steel unions are suitable for use with ASTM A 106 Grade B pipe as well as lower grades.

6.2 Carbon steel and stainless steel union parts may be forged, formed, or made from wrought bars conforming to the requirements of the melting process, chemical composition, and mechanical property requirements of ASTM A 105 for carbon steel and ASTM A 182 for stainless steel grades.

6.3 Unions may be made from materials of other wrought material by agreement between the manufacturer and the purchaser, but shall not be marked SP83.

7.TESTS

7.1 Pressure testing is not required by this standard.

8 .DESIGN AND DIMENSIONS

8.1 Socket Wall Thickness for Socket Welding Unions. The socket wall thickness shall be no less than the corresponding values, C, shown in Table 4.

8.2 Minimum Body Wall Thickness for Socket Welding Unions. The minimum body wall thickness, other than socket wall, must be equal to or greater than the nominal wall thickness of Schedule 80 pipe of the same size as the union, as established by ASME B36.10M.

8 .3 Minimum Wall Thickness for Threaded Unions. (Dimension C in Table 5).The minimum

wall thickness at the root of the pipe thread at the wrench tight plane, must equal or exceed the nominal wall thickness for Schedule 8U pipe.

8.4 Other Dimensions. The dimensions for unions capable of meeting this standard are shown in Table 4 for socket welding unions and Table 5 for threaded unions。

8 .5 Union parts from different manufacturers are not functionally interchangeable and combining parts from different manufacturers is not recommended.

9.SOCKET WELDING JNIONS

9 .1 To provide assembled union uniformity this Standard Practice establishes dimensions(Table 4

Column E) for the location of the bottom of the sockets.Socket welding union ends shad be faced at right angles to the axis to provide a flat surface against which to weld and the socket shall be counterbored or otherwise machined to insure uniform depth and circularity.

9 .2 When installing socket weld end unions, to minimize the possibility of cracking of the fillet welds, it is recommended that the connecting pipe be withdrawn approximately 0.06 inches away from the bottom of the union socket bore before welding(see Figure 1).