NDT for Pipe Fittings and Flanges

Since you are talking about the critical areas , why don't you follow the relevant codes (API for petrochem, ASME for the steam, boiler etc). These specify the requirements.

And the problem what you mentioned, looks to be as a result of plate lamination and was because of usage of a substandard plate (non UT tested)

A plate of 63 mm or so should have been UT Tested.

If procedures for procurement of fittings such as technically clear indent,T/c requirements ,Vendor selection & QC checks from your stores should eliminate the problem. 48mm boiler quality plate tested ultrasonically at manufacture's end & TC is issued accordingly.

Most of the pipelines are tested hydraulically before put into use anyway.

Practically it is not possible & required to check each fitting hydraulically if procurement procedures are strictly followed.

Hi...

In critical applications checks for subsurface defects have to be carefully and patiently undertaken. The best known methods are UT, x-ray and gamma ray examination. The testing equipment should be accurate and correctly caliberated. It is difficult to detect slag inclusions by UT. A combination of tests have to be designed and conducted during selection, procurement, on-delivery, during processing and after completion/installation. Thick walled items must be free of internal stresses and stored correctly to avoid any defect getting generated because of faulty storage. For an example i will tell you that an end shield of a Calandria (nuclear reactor) developed a hairline crack during storage. The x-rays at time of arrival were clear. The storage period was long and a repeat x-ray examination before installation was omitted because of monotony finally resulting in a colossal loss. So it is better to be always safe than sorry.

Anil Tiwari / Delhi

It is not advisable and also practically impossible to test each and every fittings from the vendor. If we follow the ASTM norms and also the standards it actually calls for the certificates which are issued by the vendor about the endurability of the materials being tested and manufactired from.

So looking out for the cheapest vendor without any certification affore3said uin ASME will lead to fatal loss which is not tolerable. So its better to go for standard vendors despite of maney savinf techniques.

Thanks,

Kumaran