What's a "Hammer Test"? 2

[Christine74]

I've seen a couple of drawings of older pressure vessels (WWII era, IIRC) that mentioned the phrase "Hammer Test" in the section that listed all of the NDE. What kind of test could this be referring to?

-Christine

 

[unclesyd]

Bring a vessel up to hydrostatic test pressure and hit each plate and welds with a hammer. This test was generally applied to carbon and low alloy steels of the day. Not use much anymore, but still a good test for burned steel.

It was and is used to test for broken stay rods in vessel, especially a boiler or heater. You have to have access to both end of the stays. You watch the rebound of one hammer to the impact of the other hammer it takes hammers.

 

[aclark]

The hammer test was taken out of the Code in the early 1950's. I was to be applied only to welded vessels rivited vessels were exempt. Welding was a "new " thing and they didn't trust it.

 

[JoeTank]

Unclesyd,
My older copies of ASME VIII call for the pressure to be lowered to MAWP before whacking on it with a hammer.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[unclesyd]

While I was involved with this practice we hammered tested Pressure Vessels at Hydrostatic test pressure and if it was a boiler component we tested around 90% MAWP.

The test procedure for a vessel stay rods was test a 0 prssure, note bad or funky stays, then pressurize to 1/4 of the MAWP and retest.

Anecdotal:
The newest man in the shop got the hammer.

In the early 50's and again in the early 60's I go to see a variation of the hammer test being used to test full size vessels made for Nickel Steels filled with LN2. They did take the man out of equation.

Not too long ago we decided to test a jacketed SS vessel with stay rods to ascertain if we could detect potential leaks. I was the inside man and on the third try one of the stays tore loose with loudest bang the earth has ever heard. Even with sponge ear plugs my ears rang for several weeks and it was a week before I could hear anything.

 

[MetalsInc]

I am sitting here looking at an inspection protocol that requires a "Hammer Test" on coatings. A medium hard blow with a 1kg hammer. No flaking, chipping, spalling allowed.

Highly technical.

 

[unclesyd]

Like that size a lot better than the 16# hammer we used.

 

[chicopee]

To hammer test properly you need to use a 10 ounce ball peen hammer. The area under scrutiny is tapped, not whacked, with the hammer. You are then listening to the sound of metal. If detriorated the metal will not have a clear sound,where as "good" metal will ring true. You also apply the technic to riveted joints. a busted rivet will sound dull when tapped. Of course you have to develop an ear for it so you should practice on sound and deteriorated metal. Highly subjective but quick. Suspect area should be further investigated as you should not be too quick on judgement.

 

[unclesyd]

chicopee,
There are several hammer tests with the one that Christine74 was concerned with was to test the integrity of the welds and heat affected zone of mainly newly fabricated or repaired vessels. The hammer use was the aforementioned 16# pounder or larger.

The test you mentioned was usually referred to as "ringing" the metal whether rivets, stays, or tie-rods. We also used the smaller hammer to survey for fire damage (burnt metal) to determine further suitability for for service. The type test you mention was a must in the railroad round houses for in service locomotive boilers. It was also used on some tank cars. Anything riveted was candidate for a few whacks

The LN2 vessel I saw under test at temperature was hit with a very large weight dropped several feet. There were 2 vessels one was impact tested and the other test to failure at temperature.

 

[chicopee]

I am not sure that I have ever seen a precise definition for "hammer test" or "ring test" but when referring to the NBIC testing staybolts with a hammer is mentioned therefore on can state that such test can be identified as a hammer test.

 

[GenB]

I use the 2Kg 'ball pein' hammer to test small steam boiler shells, the min t is 1/4in and if it has lost wall t to corrossion the hammer will indent the metal if the wall is less than 1/8 thick (you go easy on it or you will destroy the boiler)
genb

 

[deanc]

GenB:

Must comment----if the wall is thinned to half the t-min. you may be doing a service to "hole it". Sounds like a good way to avoid some unnecessary death.

Check some of the old stds.for A-139,spiral weld pipe. "Strike weld with 3# hammer under full hydro".I don't see it in there anymore,must of ran out of employees.