2" weldolet on 8" pipe with less weld material than spec.

[forumoil]

Hi, what would be best practise to calculate an estimated risk to allow a limited time of operation with:

# 2" weldolet on a 8" pipeline
# Estimated weld on weldolet = 12-13mm
# Pipeline WT = 18.26mm

The spec says weldolet weld must be of larger extent. Is there any best practise how to proceed with a quality insurance for a limited period of operation?

Thanks in advance.

 

[metengr]

forumoil;
There is no best practice for shortcuts when it comes to personal safety and equipment reliability. You follow rules in the applicable piping code of construction for sizing the weldolet and attachment weld. Nothing more nothing else.

 

[Ballbearing1]

forumoil,
I agree totally with metengr regardinging the safety aspect but what you must realise is that the amount of weld required is based on the nominal thickness of the branch connection (weldolet) and not the thickness of the main pipe.
What is the welding code ?
If it is B31.3 have a look at 328.5.4 and Fig 328.5.4D
Regards,
BB

 

[forumoil]

Hi, metengr, first i want to clear any misunderstanding. This is not about "shortcuts", safety will always be first priority! That’s why it is to be evaluated. Maybe my words were not accurate enough to present my challenge. Let me try rephrase

How would you approach to evaluate a welded weldolet on existing pipework as described in opening message?

Hi, Ballbearing1, this weldolet doesn’t look like the ones described in ASME B31.3 -2008
I used google and found a typical view how it looks like:

http://www.gobizkorea.com/att/cat/1999-07531/tp_html/img/1999-07531_cat_5_large_img1_2.jpg

Hopefully this presented the challenge in a better perspective and I repeat it’s not about a shortcut; it’s about how to perform a qualified evaluation of a welded weldolet to make sure it’s safe and mounted according to specs.

I struggle to find appropriate reference how to evaluate the weldolet integrity.

Thanks in advance

 

[metengr]

forumoil;
I would suggest you go to the web site below to understand how a weldolet is supposed to be sized and attached to a main pipe run. Look for Branch Connection Catalogue, they describe the minimum required weld size for a weldolet.

http://www.bonneyforge.com/

 

[Ballbearing1]

metengr,
I printed the bonney forge document but cannot find a reference to minimum weld size. The only thing I can find is on page 35 where it states you only need to weld to the "weld line" which is the beveled portion.
Regards,
BB

 

[metengr]

BB;
You are correct. The weld size is governed by the edge of the bevel and that is what needs to done to assure adequate strength in service. I really don't see any problem.

If you use less weld metal you have higher stress intensification, resulting in greater susceptibility to fatigue crack initiation and propagation in service. How much more risk does one need to take by not following the manufacturer's recommendations for their fittings?

 

[Ballbearing1]

metengr,
I am a little confused, maybe you can clarify.
B31.3 328.5.4 states that Figures 328.5.4 A through 328.5.4E are applicable when the branch pipe is attached directly to the run pipe. This is not applicable in this case as we are discussing a weldolet.
However, 328.5.4 (d)states "Branch connections, incuding branch connection fittings.....shall be attached by fully penetrated groove welds...... and shall be finished with cover fillet welds..."
The diagrams in the bonney forge spec show the weld as being only flush to the edge of the bevel, no fillet welding added.
Your thoughts ?????
Cheers,
BB

 

[metengr]

BB;
You need to review the applicable sketches with 328.5.4 (d). Also, there is reference to 300.2 and 304.3.2 in this same sentence. The reason for the cover fillet welds is to reduce stress concentration. Look at the profile of the finished weld for the weldolet and you will see that an additional cover fillet weld is not required because following proper fill of the bevel joint, the weldolet by design provides adequate reinforcement for a branch connection.

 

[Ballbearing1]

Thanks metengr,
After reading 304.3.2 again I think I understand it now.
Not sure about your statement on 328.5.4(d), I thought that was only applicable for a branch pipe connected directly to a run pipe ?
Regards,
BB