Weld Durability

Too many other factors are in play to say yes or no to such a question.

Depends on the weld, the direction and magnitude of the vibration, the materials join and the surface area of the joint.

Only crap ones.

a welder with many years of experience told me socket welds were avoided in shipbuilding because they are prone to cracking due to vibration. Therefore should they be avoided on a gas turbine even with the reduced vibration?

That can be said about all welds. Not enough information.

If it is a properly done weld by a skilled welder then refer to answers 1-4. Since you are asking us your answer is probably yes.

You may want to have the weld stress relieved depending on materials and environmental concerns.

Are socket weld more prone to cracking when subject to vibration?

As compared to something welds not subject to vibration, yes.

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Are socket weld inherently more prone to cracking under fatigue loading conditions?

Socket welds, especially those welded in a no-gap condition, can be unduly subject to cracking.

Would this depend on how you are using socket welded components? They might not be worth poo as a sleeve bearing for example.

A socket weld has a sharp notch built into the root of the weld. I vote yes if you are comparing it to a full penetration weld when considering fatigue fracture as the primary failure mode.

Regardless of weld pattern, size and material, simultaneously minimizing thermal distortion and achieving physical/structural continuity of the weld is welding's Holy Grail. (Ok, you may be able to take spot welds off the list.). If you can, broaden beyond 90 degrees the face angle available for weld contact on abutting surfaces. (BTW, if anyone has ever seen this over-90-degree feature on a stock item fitting or sleeve, sound off.)

Finally, if you are affixing a solid shaft (or any connection where axial alignment is critical) to a deep sleeve of comparatively rather modest wall thickness, consider cutting opposing matching groove patterns (one or two pairs) a short distance back into the sleeve wall. You can start the weld program by tacking the crotches of opposing grooves while sequentially checking shaft alignment, with alignment adjustments made more readily than tacking on the face of the sleeve absent the grooves.

Butt welds are better than socket welds in terms of strength and resistance to vibration, stress, fatigue, corrosion and erosion.

However, socket welds are often used on small diameter pipe and fittings since they are far easier to perform than butt welds. Their limitations should be taken into consideration:

• Fillet weld failure resulting from thermal expansion of pipe with insufficient gap at bottom of the socket.
• Fillet weld fatigue due to vibration, stress and temperature fluctuations.
• Corrosion due to internal crevices.
• Erosion due to internal irregularity.