Welding A217 C5 valve into a plain carbon steel line

[Trebormech]

I am looking at the replacement of a check valve in a boiler feedwater line. The new valve is 5% Cr cast. The piping is A106 CS. Can this be done with the proper preheat, PWHT, and electrode selection? Is this weld even allowed in the ASME boiler code? Would there typically be a buttering process needed for the weld procedure?

Thank you.

Trebormech

 

[Dhurjati Sen]

Ask this in the welding forum. It seems you are only interested in the welding procedure. However, why is the valve welded and not flanged?

DHURJATI SEN
Kolkata, India

 

[Trebormech]

Thank you, Dhurjati Sen.
All of our boiler feedwater piping and valves are butt welded. This is common for our industry.

 

[Dhurjati Sen]

What is the pressure? Approx 100 kg/cm[sup]2[/sup] ?

DHURJATI SEN
Kolkata, India

 

[Trebormech]

12,410 kPa (1800 psig)

 

[0707]

IMO this can be done with the proper preheat, PWHT, and electrode selection. Before start qualify your welding procedure

luis

 

Yes, it can be done with the proper preheat, PWHT, and electrode selection AND input from a Welding Engineer.
For those intending to mess around with alloy steels I strongly advise it.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Trebormech]

Thank you for your replies.

As both materials are included as acceptable materials in the BPVC and ASME B31.1, I do not believe that welding them together poses any issue with code compliance. So, it's really about the weld procedure.
Would it be easier to weld P11 (1 1/4 Cr) or P22 (2 1/4 Cr) pipe stubs to the valve as a transition from CS to 5% Cr as far as weld qualification goes?

 

[weldstan]

You'd be better off with a P22 transition.

 

[0707]

Yes I agree with weldstan because of cromium dilution on HAZ

luis

 

No HAZ ever suffered from dilution. It is base metal.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[0707]

Ironic

where is the HAZ?

luis

 

On either side of the weld metal.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Dhurjati Sen]

Nobody is sharing the welding procedure. It is funny.

However, as the pressure is approx 100 kg/cm2, even a little more than that, welded valves is the norm. A quick search at the project stage documentation would yield the desired welding procedure. Only the electrodes that were used might have been obsolete.

DHURJATI SEN
Kolkata, India

 

To all experts and not-so-experts:

By throwing up partial answers and unrelated opinions (or even correct answers) based on minimal information you are only enabling amateurs to do critical joining operations on equipment with serious safety implications. Steam is hot and downtime is costly!

You can find anything on the interweb, but I will remind everyone that: (i) welding procedures do not make welds; and (ii) Code compliance is necessary but very far from sufficient. Remember your professional obligations.

IM



"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[0707]

either side of the weld metal is where ironic?

luis

 

At an obtuse location.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

While the A106 to 5-Cr valve can be made without a transition pup, the PWHT temp is essentially limited to 1340F max, the lower critical temperature of low carbon steel as provided in B31.1. This limiting factor may require added time to the PWHT to provide adequate stress relief for the 5-Cr side of the joint depending on service requirements. It will also influence choice of welding filler metal. The use of the P22 pup will permit a higher PWHT temp to be used for the P22 to 5-Cr but the CS to P22 weld will still be limited to 1340F max as previously stated.

You don't state why the 5-Cr material was selected nor the operating temp. I have only known of 5-Cr being used in the stated or similar service was to provide protection from high velocity erosion of the previous CS equipment.

You really should hire a welding metallurgist/engineer to review the service conditions and write the WPS for qualification to meet the intended service.

 

[0707]

Your own words ironic

At an obtuse location.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

luis