300 % NDT for pipeline CODE DNVGL ?? 1

[R. Pradhan]

Hi All
we are doing pipeline project and base is DNVGL
client is asking for 300 % NDT for all girth weld when using manual UT
is it required 300 % ??
Also is it compulsory RT + UT (Manual ) ??
me or my team do not have experience on this please guide

best regards
Pradhan

 

My dad, who had grade 8 education, taught me that you cannot have more that 100% of a thing.
(Excepting NFL players being interviewed of course.)

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

Ask the client what he means. And is the requirement in the contract specifications?

 

[gtaw]

If you don't like the results of the first round, do it again (that's twice or 200%), if you don't trust those results, do it again (300%).

RT has an increase probability of detecting a discontinuity if the major axis of the discontinuity is parallel to the radiation. The probability of detecting a discontinuity with UT is maximized if the major axis of the discontinuity is perpendicular to the sound beam.

If the crack is a throat crack extending from the root through the weld to the face of the weld, RT will have little problem detecting it. If the discontinuity is a lamination in the plate, RT is unlikely to detect it. In the case of a lamination, UT will have little problem detecting it.

Best regards - Al

 

[R. Pradhan]

thanks everyone for reply
BASE ON DNVGL -F101- 2017
Still Client is forcing to do UT+RT+MT where as it DNVGL - D.1.4.4 it is optional
and somewhere it is saying we have to go for UT +RT so bit confuse
please guide

APPENDIX D NON-DESTRUCTIVE TESTING (NDT) ( Page – 392/393)
Methods of NDT shall be chosen with due regard to the conditions influencing the sensitivity of the methods. The ability to detect imperfections shall be considered for the material, joint geometry and welding process used.
D.1.4.2 As the NDT methods differ in their limitations and/or sensitivities, combination of two or more methods shall be considered since this is often required in order to ensure optimum probability of detection of harmful defects.
D.1.4.3 Magnetic particle, eddy current or magnetic flux leakage testing is preferred for detection of surface imperfections in ferromagnetic materials. For detection of surface imperfections in non-magnetic materials, either liquid penetrant testing or eddy current testing shall be preferred.
D.1.4.4 Ultrasonic and/or radiographic testing shall be used for detection of internal imperfections. It may be necessary to supplement ultrasonic testing by radiographic testing or vice versa, in order to enhance the probability of detection or characterization/sizing of the type of flaws that can be expected, as specified in [10.5.3].
Radiographic testing is preferred for detection of volumetric imperfections. For material thicknesses above 25 mm radiographic testing should always be supplemented by ultrasonic testing.
Ultrasonic testing shall be preferred for detection of planar imperfections: Whenever determination of the imperfection height and depth is necessary, e.g. as a result of an ECA, automated ultrasonic testing is required. The sizing accuracy and POD has to be documented to be adequate for use with the applicable ECA derived acceptance criteria.
D.1.4.5 When manual non-destructive testing in special cases is used as a substitute for automated ultrasonic testing for pipeline girth welds, both radiographic and ultrasonic testing of the girth weld shall be performed.

 

[weldstan]

The Code requirements are quite clear. As a minimum 2 NDE methods are required. And if manual UT is performed, 3 NDE methods are required. So your clients requirements for MT, RT and UT testing of circ welds are not excessive.

 

[DekDee]

DNVGL-ST-F101 is the standard for Submarine Pipeline Systems (Subsea).
If you and your team have no experience with this you are in a world of trouble.

 

[R. Pradhan]

Dear
Thanks everyone for your support
Regards
Pradhan