Spigot and socket joints in B31.3??? 1

[Jaypeet]

We have located a number of spigot and socket joints on a 60+ year old 300NS steam line. Basically normal pipe end inserted into a belled pipe end (socket) and then closed with a fillet weld. Does anyone know if we can possibly qualify this type of joint against B31.3? Any help on the limitations of this joint type would be a good start!

Regards

Jay

 

[deanc]

Have fun. I would not be surprized if this line was not oxy-fuel welded. If you decide not to replace it see the NBIC Part RB for starters.

 

[MJCronin]

jay,

Properly socket-welded fittings are permitted by ASME B31.3...

However, this piping code puts limitations on:

- the fitting to be used (typically dimensioned to ANSI B16.11)

- the size and type of fillet weld

- the maximum piping diameter, typically 3"NPS

- the type of fluid service, lethal and flammable service sometimes excluded by clients

I doubt if your 60 year old piping system was built to any piping code......I seem to remember that ASA B31.1 was first published in the early 1940's

MJC

 

[bvi]

See 318.1.2. For joints using unlisted components, qualify the joint for pressure design per 304.7.2. The socket weld fillet dimensions in 328.5.2 are not necessarily sufficient for piping loads, so you should also do a stress check on the fillet.

 

[bijuvh]

Hai Jay,

Here are some standards, but not limited to be studied in detail to find solution for your case

API SPEC 5L Line Pipe
ASME B31.3 Process Piping
ASME SEC IIC Welding Rods, Electrodes and Filler Metals
ASME SEC V Nondestructive Examination
ASME SEC IX Welding and Brazing Qualifications
ASTM E92 Vickers Hardness of Metallic Materials
ASTM A833 Indentation Hardness of Metallic Materials by Comparison Hardness Testers

Biju V H