AISI 4130 V/s API 5L X-60 1

[metboss]

Dear All,

We have some requirements for Welding connector (API 5L X-60 grade, 30" Wall thickness 1"). This connector will be welded to Conductor Pipe (API 5L X-52, 30" Wall thickness WT 1") at Drilling Rig site.
But our suppliers are offering below material specs. for Welding connector.
Supplier 1: Welding connector w/material grade AISI 4130 60 KSI (forge) w/ Carbon equivalent (CE value): 0.7-0.73.
S2: Welding connector with material grade AISI 4130 90 KSI (forge) with Carbon equivalent (CE value): 0.71-0.73
S3: Welding connector with material grade AISI 4130 100-110 KSI (forge) with CE value: 0.73-0.75
Our suppliers are claiming that all above mentioned grades are compatible and there will be no weldability issues with Conductor pipe material grade API 5L X-52.

My queries are as:
• Can we accept all above mentioned substitutional grades (yield strength: 60 ksi or 90 ksi or 100 ksi)?
• Is there any weldability issue with AISI 4130 90 ksi or 110 ksi material (high yield)?
• As per our standard, the maximum CE value is 0.43; but, suppliers proposed CE values ranges from 0.70 to 0.75. What is the
average CE value for AISI 4130 forging material?
• If we accept any of the above grades (60 or 90 110 ksi), what are the precautions to be taken w.r.t. welding at Rig site
(Welding of AISI 4130 90/110 KSI with API 5L X 52)?

Any advice is highly appreciated.

 

[weldstan]

With a properly qualified welding procedure and adherence thereto by your field welders and inspectors, you will have no problem welding 4130 to the pipe grades stated.

 

[blacksmith37]

From a refinery /pipeline side ; you are playing with fire. I know this is commonly done by production people . Because it is production ,there is a risk of sour conditions at some time . The strength of your 4130 starting material has nothing to do with it ; your risk is in the HAZ of the 4130. You need someone who knows what they are doing to develop your WPS . The PQR needs to have micro-hardness traverses across different parts of the HAZ. I suggest 30 Kg Vickers , big enough to see but still micro hardness . I would set the acceptable hardness at HRC 23 equivalent. With the implied wall thicknesses , I think you are talking about 400 F preheat . To reduce headaches , I would stay with the 5L pipe ,even if it means new vendors.

 

[weldstan]

Listen to blacksmith37 regarding WPS qualification. I too would recommend using a low carbon steel for the connector.

 

[metboss]

Thanks for above advice from Blacksmith and Weldtsan.
However, our application for Conductor Casing installation and there will be no exposure to H2S/CO2 corrosion. Our concern is on weldability with high yield AISI 4130 material (especially 90 and 100 ksi.
Considering the urgency of Rig operations and lesser supply lead time, I was instructed to accept AISI 4130 90 or 100 ksi material from supplier S2 or S3. Have you come across such welding? Was there any delayed cracking after welding? Any further advice will be highly appreciated.

By the way, what is the nominal/avg. Carbon come Equivalent (CE) value for low alloy steel AISI 4130 material?

 

[saplanti]

Why cannot you try ASTM A 694 F60 forged piece as the connector? This is the material used for flanges with the line pipe Material you mentioned.

 

[gtaw]

AISI 4130 can be welded if the proper procedures are followed and conditions met. This is a chrome/moly steel with about 0.3% carbon. One must note the processing (heat treatment) the component was subject to by the manufacturer. The Ce is relatively high, so preheat and possibly post weld heat treatment must be considered.

I had a contractor insist on welding 4130 pipe without preheat or post weld heat treatment. The CVN values were in the single digits and the tensiles rather high. The bends; I don't remember them passing, but even if you give them the benefit of doubt, everything else was not good.

"But that's how we always do it!" Unfortunately, the material only had to meet the specification for piling. The only criteria was the minimum tensile strength, so the chemistry from one lot to the next is anyone's guess.

Al

Best regards - Al

 

[weldstan]

I have developed such welding procedures without PWHT and qualified per ASME IX over 40 years ago with success. It can and has been done by others as well.

 

[gtaw]

It depends on the thickness of the coupons, cooling rate, etc.

Best regards - Al

 

[metboss]

Thank you all for your input.

Considering the urgency and supply lead, we may have to select AISI 4130 100 KSI/110 KSI material for Connector. Meanwhile, I have contacted our local welding service provider and requested for WPS (AISI 4130 110/110 KSI V/s API 5L Gr. X-52).
But, they submitted the WPS for base metals AISI 4130 75 KSI and API 5L Gr. X-52.

Can we accept this WPS? Is there any restrictions w.r.t yield strength variations (100/110 KSI to 75 KSI)? Is this an essential variable?

 

[19Delta]

my experience is in drilling tools however, can you tell us what kind of connection BX , RX , hammer union? Considering the amount of time it takes to develop a weld procedure it may be better to continue searching for 5L material.

 

[blacksmith37]

Before I retired ,Vetco was using 5L pipe for weld-on casing connectors to avoid welding complications of Cr : Mo . Refineries weld Cr: Mo every day ,with preheat , post heat ,and carbon less than 0.3 %. It just costs money.

 

[metboss]

Quick connector- One end is Pin thread (proprietary thread) and the other end: Bevel for proposed welding with Conductor pipe (API 5L Gr.X-52).

Finally, one of our bidder offered us AISI 4130 75K material (yield) for Connector and we accepted it as qualified WPS is already available (for same material grades) with our local Welding service providers. The qualified WPS includes both Pre-heat and PWHT and they used it for many past jobs with successful results.

Thank you all for your valuable inputs.