Socket Weld VS Butt Weld (Joining or Fittings)

This is the sort of thing that can be sorted out over the telephone with the local friendly piping distributors, i.e. the ones that are going to quote for the materials. After all, it is in the supplier's interests that the correct materials are shipped to site, as it doesn't want any come-back for supplying ones that are wrong. Make the call.

wahaimach,

You did not share:

a). how much total piping you have

b). the breakdown of the sizes

c). the quantity of each size

But I recommend that you consider using "Bends" where ever possible to reduce the number of joints (Socket welded or butt welded).

wahaj...

There has been some literature published regarding fatigue failure of socket welds in hydraulic systems. These are systems that are subject to repeated pressure pulsations.

However, quality welds in butt-welded pipe of smaller sizes is difficult to achieve

Black steel (A53) schedule 40 is good to a working pressure of about 1800 psig (up to 2" size)....not the 3500 psig that you claim. What is your source of information on this wild claim ?

The advice Pennpiper gave you about using bends instead of socket fittings is, as always, good advice.

Have you ever been involved in piping system design before ?

Have you considered a mechanical means to dampen out pressure pulsations?

Thank You for the reply.

I am more concern on Socket weld or Butt Weld.

We are upgrading a site, it requires around one kilometer of 2 inch pipe for hydraulic system.

Existing site has hydraulic system with socket weld, but they are not in use from decades.

My site is link with the existing site. After exploring on Internet, I found that buttweld is better but consume time.

and the Strength of fillet weld is 1/3 of buttweld.

as you said, fatigue failure of socket weld.

But the socket weld fittings has withstand pressure 3500 psi and were as butt weld fiitings has 1500 psi.

i heard that the hydraulic system pressure is around 80 to 100 bars?

Help me in selecting the type, butt or socket , with reference.

thanking you

wahaj

Simple answer to your question that which type of joint between socket weld vs butt weld - is of course butt weld. But this is not the end. When you select to make weld joint, then the question arise which process of welding you are applying. In my opinion Tungsten-Inert gas-Welding would be the best. You may choose to Metal-Inert gas-Welding, if the thickness of pipe mandates. Now welding of small dia pipe (2"NPS and below) need a perfect jig to align and to make root gap. But you cannot use jig on each weld due to location and confined space. Consequently either you make imperfect weld and misaligned joint. To over come these problem it is recommended to select socket type joint. Now socket weld, when seal welded, some time cracks due to pressure, heat or expansion during operation. To overcome this problem most recommended is the use of "Socket Weld Contraction Ring". This ring is made of stainless steel and according to size and thickness of pipe and socket fittings. The ring is inserted into the socket fitting first then pipe perfectly squared face pushed till it is stopped by the ring and seal welded. When you fillet weld the joint it holds the pressure and the effect of pressure and temperature.

Regarding weld strength, you would not find any specification or table to compare. You would have to determine by yourseolf, subjecting it to destructive test/tensile strength testing with tensile testing machine/jig.

Regarding pressure rating, it varies depending upon wall thickness, allowable stress and temperature of the product. I cannot reproduce the table here, but you can find it on page # 103, Piping Design and Engineering Hand Book, Published by Grinnell Corporation.