Welding on a compressor tank :-(

You (meaning the average "dauber" welder) DO NOT EVEN THINK ABOUT welding on a pressure vessel. Anyone who does it for you (especially for cash money) has his ass hanging out a mile and a half for liability - this is a specialized field with lots of pitfalls.

If you really want it fixed, you need a certified boiler and pressure vessel welder to do the work. They do exist, these are the same people who weld in new crown sheets and repair patches on old steam engine boilers and large stationary boilers.

They have to match the type and gauge steel used in the tank, roll the patch to the proper curves, use the proper welding wire or rod, pre and post heat treat as needed, repair any staybolts or attachments as needed, X-ray or otherwise check their work (and for any other latent problems they might have missed) and then hydrotest.

But a brand new factory built tank is probably cheaper than paying someone to repair and recertify the one you have. And this time, mount the compressor remotely.

The reason they spend a lot of money to repair those historic boilers is repair is still cheaper than building a new boiler to the exact old dimensions from scratch - and then rebuilding the entire vehicle around it. Or in the case of a huge power plant, wrecking the old and erecting an all-new boiler in the same space - they don't ship well when you get up in the million pound range...

Or they don't want to destroy any 'historic value' of a steam engine with an all new duplicate boiler, which is silly if they duplicate it faithfully (well, except for the lap-seams and rivets...) and they reuse the chassis and all the old running gear.

There are times when safety trumps perfect historical accuracy, and this is one of them - the aftermath of tanks and boilers going BOOM!! is not pretty.

-->--

Reply to
Bruce L. Bergman
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I disagree with that, Jon, based on data from the AWS Pressure Vessel welding reports I've seen over the years. The expansion/contraction due to pressure increases and decreases is a minute fraction of the fatigue loads imposed by vibration.

True fatigue, as I said, is a very strange phenomenon. There are all sorts of failures we commonly call "fatigue," but true fatigue often behaves very differently from what many people expect. It's the product of number of load cycles imposed at some large fraction of the elastic limit, and it varies widely by material type. For aluminum, for example, that expansion/contraction due to pressure changes, as in a jet airliner, can indeed fatigue the material to failure. In steel, that isn't likely to happen. Steel is vastly more resistant to fatigue than aluminum is. Fatigue cycles to failure for steel usually are measured in the tens of millions of cycles. That's a lot of expansion and contraction, but maybe only a few years of vibration cycles, given the normal uptime on a compressor in commercial service.

-- Ed Huntress

-- Ed Huntress

Reply to
Ed Huntress

If you don't remount the motor and compressor on some kind of resilient mount, the original copper tube should still be fine.

Reply to
Edwin Lester

how many ignoramuses are there here? well I stay at sci. engr....... do you have lots of email addresses/user names?

What if the issue could be considered a design defect instead of a vibration crack. Or a defect in original workmanship. re design or and do better workmanship.

I know a friend who had a commercial welder cut out and put in a new pipe thread fitting for the drain spigot at the bottom of a tank. So some folks with liability issues will weld on tanks.

Fran

Reply to
fran...123

The obvious answer is weld the tank, and then bury it deep enough so that if/when it explodes, no one gets hurt......

Reply to
David Lesher

Too_Many_Tools fired this volley in news: snipped-for-privacy@g1g2000pra.googlegroups.com:

That's spelled, "Build a _real_ barbeque" .

LLoyd

Reply to
Lloyd E. Sponenburgh

But then will have to call you

pIggy :-)

--.- Dave

Reply to
Dave August

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