PQR Preheating

[PipinFool]

I am in the process of establising some new PQR's under API 1104 code, section 5.
The pipe grades to be tested will be the norm for the pipeline industry:

X-42, X-60, X-65 and X-70

Weld Processes to be used:

SMAW cellulose electrode
SMAW cellulose + lo-hy electrode
GMAW
FCAW

My question is, how do I determine what should be preheated?

I planned on determining hardness values in the HAZ. I have conflicting information as to what HV values I should shoot for.

Should I be looking at other alternatives?

Any information whould be greatly appreciated.

Thank you.

 

[stanweld]

Preheat per 7.11 & 5.4.2.14 of API 1104 will depend on metallurgy (CE) of base material and deposited weld metal, thickness of base metal and atmospheric conditions. If you have hardness requirements, preheat must also be adressed. As CE and thickness increase and as ambient temp and hardness requirements decrease, the preheat temp must increase to mitigate cold cracking decrease hardness.

 

[stanweld]

Oops. 5.4.2.14 should be 5.4.2.13. Also refer to 5.3.2.13.

 

[rneill]

If this is a sour service then unless the end user has some more stringent requirements, I would look to NACE MR0175/ISO 15156 for guidance on the hardness testing required in the weld procedure qualification and for the acceptance criteria.