Pipeline post weld heat treatment 1

[pipeliner3000]

On a typical pipeline automatic welding spread how soon after the last weld run (fill and cap pass)can/does PWHT take place i.e. how many joints after and typically how long would PWHT process be for heavy wall pipe around 10"?

 

[metengr]

What is the material and wall thickness??????

 

[pipeliner3000]

API 5L X60 50mm wt

 

[metengr]

Regarding PWHT for P-No 1 or S-No 1 base material, there is no requirement for delay of PWHT, this can be done anytime after the weld is completed provided the welds are protected from exposure to harmful forces or stresses prior to PWHT. For PWHT requirements, review ASME B31.3, Table 331.1.1, normally 1 hr/inch (or 2.4 min/mm) of nominal thickness.

 

[stanweld]

The time duration is not addressed in ASME B31.4 and B31.8. As a practical matter and assuming the pipe is to be buried, it should be done as rapidly as possible after required NDE to permit ongoing joint wrapping and burial activities.

 

[pipeliner3000]

Would NDE (proposing AUT) be carried out before PWHT.. is this usual?

 

[metengr]

For S-No 1 base material, NDE can be carried out before PWHT. Is this usual, lets say it's typical.

 

[Ron]

PWHT should be done immediately. NDT should be done after PWHT.

 

[grampi1]

Make sure field PWHT is at a temp colder than mill temper or some strength will be lost.

 

[pipeliner3000]

I'm assuming S-No 1 base material is applicable to API5L X60 line pipe steel with heavy wall.

Ideally we want to carryout AUT straight after welding this allows tight process control and fewer defects for repair if the spread has problems. If we wait until after PWHT given time for each joint (hours)then the spread is gone and process control lost.

 

[metengr]

That is fine for this application. There is NO code requirement for NDT to be performed after PWHT. In other words, as long as welding is completed, NDT can be performed. If a client requests NDT to be performed specifically after PWHT, this is their choice and must be followed.