. Fundamental needs for the look of ERW straight seam steel pipe welds
Prior to the non-destructive testing of straight seam steel pipes(ERW pipe), the look inspection of welds should satisfy the needs. The overall needs for the look of straight seam steel pipe welds and also the surface quality of welded joints are listed below:
The look of welding ought to be well created, and also the width ought to be 2mm within the fringe of the groove on every side. The peak from the welding ft of fillet welds should satisfy the design needs, and also the shape should transition lightly.
Welded joint surface:
(1) Cracks, unmelted, air holes, slag inclusions and splashes aren’t permitted.
(2) Tthere shouldn’t be undercut around the weld the surface of pipes having a design temperature less than -29 levels, stainless and alloy steel pipes having a greater inclination to harden. The undercut depth of welding seam of many other materials will be more than .5mm, the size of continuous undercut shall ‘t be more than 100mm, and also the total period of undercut on sides from the weld shall ‘t be more than 10% from the total entire weld.
(3) The top of welding seam shall ‘t be less than the top of pipeline. The rest of the height from the welding seam is only 3mm (the utmost width from the welding joint group towards the rear groove).
(4) The incorrect fringe of the welded joint shouldn’t be more than 10% from the wall thickness and never more than 2mm.
2. Surface non-destructive testing
The choice principle from the surface non-destructive testing way of straight seam steel pipes: for ferromagnetic material steel pipes, magnetic particle testing ought to be employed for non-ferromagnetic material steel pipes, transmission testing ought to be selected.
For welded joints which have a inclination to obstruct cracks, the top non-destructive inspection ought to be performed following the welding is cooled for any certain time period for welded joints which have a inclination to reheat cracks, the top non-destructive inspection ought to be performed once after welding after heat treatment.
The use of surface non-destructive tests are transported in compliance using the needs from the standard. The recognition objects and applications are usually the following:
(1) The standard inspection from the outer top of the pipe material.
(2) Recognition of surface defects of important butt welds.
(3) Recognition of surface defects of important fillet welds.
(4) Recognition of surface defects of welding sockets of important socket welding and bridging three-way branch pipes.
(5) Recognition of surface defects after pipe bending.
(6) Bevel recognition of welded joints with bigger material quenching inclination.
(7) Recognition of non-austenitic stainless pipe grooves whose design temperatures are less than or comparable to minus 29 levels Celsius.
(8) Welding seam of double-side weldment specified rooting inspection after rooting
(9) When oxyacetylene flame can be used to chop welding fixtures on alloy pipes which have a inclination to harden, the defects from the repaired parts are detected.
3. Ray recognition and ultrasound recognition
The primary objects of radiographic testing and ultrasound testing are butt joints of straight seam steel pipes and butt joints of butt welded pipe fittings.
Selecting non-destructive testing methods will be in compliance using the design documents. For that recognition of welded joints of titanium, aluminum and aluminum alloys, copper and copper alloys, nickel and nickel alloys, the ray recognition method ought to be selected.
For welds having a inclination to obstruct cracks, the radiographic and ultrasound tests ought to be performed following the weld has cooled for any certain time period.
Once the primary pipe within the jacket includes a girth weld, the weld will be 100% radiographically inspected, and also the hidden operation might be transported out after passing pressure test.
The welded joints taught in reinforcing ring or even the support pad around the pipeline will be 100% radiographically inspected, and will be covered after passing the exam.
For that welds needed for intermediate inspection of welding, non-destructive testing ought to be transported out following the appearance inspection is qualified, radiographic and ultrasound testing ought to be transported out following the surface non-destructive testing , and also the welds which have been inspected could be welded once they are qualified.