03:25 Oct-26-2005 J. Mark Davis Teacher, And Consultant University of Ultrasonics, Birmingham, Alabama, USA, Joined Mar 2000 85
Re: a question I have performed UT of piping 2 inches in diameter with a wall thickness of .100 inches using OD Creeping Waves.
Generally, materials of .200 inches in thickness can be examined with high angle shear waves.
By Code, the goal is to inspect the weld volume and heat affected zone. This may require one or more refracted angles.
Another option is using Phased Arrays where you can sweep the angles (60 to 75 degrees)with electronic scans (Sectorial Scans) to cover the volume of weld and HAZ.
Contact Olympus/ RDTech regarding applications of Phased Array.
J. Mark Davis
----------- Start Original Message ----------- : what is minimum thikness that we can use ut for welding of piping ? where standard write it? : please send me info as soon as : by thanks ------------ End Original Message ------------
08:36 Oct-26-2005 Juan Amado Engineering, Inspection Arco Industrial, S.A., Panama, Joined Nov 2001 44
Re: a question In theory Ultrasonic testing can be applied to a range of different thicknesses, from very thin using surface waves, to thick materials using different diffracted angles and low frequencies. In practice, however, inspection work would probably be performed in accordance to a standard, which will in turn place some constraints on some of the variables related the work being performed. For example, the AWS D1.1:2000 Structural Welding Code, pp. 203 states that the procedures for ultrasonic inspection described in that document are for testing groove welds and heat affected zones between the thicknesses of 5/16" and 8". Other thicknesses may be tested, but require special approvals, and procedures. Similarly you will find that in other codes or standards, different rules apply.
Hope this helps, Juan Amado
----------- Start Original Message ----------- : I have performed UT of piping 2 inches in diameter with a wall thickness of .100 inches using OD Creeping Waves. : Generally, materials of .200 inches in thickness can be examined with high angle shear waves. : By Code, the goal is to inspect the weld volume and heat affected zone. This may require one or more refracted angles. : Another option is using Phased Arrays where you can sweep the angles (60 to 75 degrees)with electronic scans (Sectorial Scans) to cover the volume of weld and HAZ. : Contact Olympus/ RDTech regarding applications of Phased Array. : Sincerely, : J. Mark Davis : : what is minimum thikness that we can use ut for welding of piping ? where standard write it? : : please send me info as soon as : : by thanks ------------ End Original Message ------------
we use B31.3 ANSI we work in amoniak plan (petrochemica plan)
WE&INSPECTION THINK DIFRENT SOME ONE SAY MUST BE TEST UP THICKNESS UP 20&SOME ONE SAY WE CAN TEST UP 8 mm in thickness but in asme sec IV we didnot see any thing about the limited thickness at now we searching by some one who read some thing about this
02:41 Oct-28-2005 Ed Ginzel R & D, - Materials Research Institute, Canada, Joined Nov 1998 1208
Re: a question Mark and Juan make good points. Yes, a high angle compression mode (the so-called OD creeping wave) can be used, but with a wavelength of 1.2mm on the 2.5mm (0.100 inch) wall Mark referred to, there is not much other than detection of surface conditions that can be done (no real flaw detection as we would traditionally do in heavy wall sections). Also, with the high-angle compression mode you need to do your detection in the first 10-12mm of distance from the probe as there will soon be mode converted signals arriving as well.
Juan points to the limitations stated by some codes. AWS is burdened by the gross dimensions of the mandatory probes so even the limit of 8mm is relying on several skips to get to the weld zone in most cases. ASME B31.3 does not have such a limit stated. But neither does it have strict requirements placed on the probe that is to be used. I have worked with phased array configurations on 5.5mm wall but the interpretation can be very tricky due to the boundary effects. Even using a small 6mm diameter probe on a 5.2mm wall (this would be the nominal for 2.5 inch diameter Schedule 40 pipe) is problematic. The dimension of the pulse leaving the wedge means that the lower portion of the pulse arrives at the ID before the upper portion leaves the wedge. Even before the main pulse centre-of-beam has reached the inside surface the back of the beam has reflected off the inside surface. Before long you have 2 or 3 pulses arriving very close to one another and again there is no practical way of a sensible "flaw detection" where you plot the defect using trigonometry. Added to these issues will be the effect of the curvature of the pipe and its effect on spreading the beam.
Attached is a model of a pulse in a 5.2mm thick cross-section. It shows the "half-skip" and two reflected portions occurring just before the centre-of-beam makes a full skip. Some success can be had using a focusing effect with a phased array setup but even this has limits for focusing. Lower elements used for focusing at higher nominal angles (>60Â°) suffer apodisation at the second critical angle. If too many elements are used the upper elements then try to contribute to the focus using angles smaller than the first critical angle and annoying compression modes are introduced.
02:06 Oct-30-2005 A.A.AMIRI Consultant, NDT/QC/WELD INSPECTION Iran, Joined Nov 2005 20
Re: a question ----------- Start Original Message ----------- DEAR SIR, IN COMMON & PRACTICAL TECHNIQUE OF UT (pulse echo)BY MANUAL EQUIPMENTS & CONTACT METHOD,MINIMUM THK. FOR OBTAIN BEST RESULT OF EVALUATION,IS 10 mm.BUT AS PER AWS-D1.1 MIN.8 mm.& ACCORDING TO ASNT UT LEVEL III STUDY GUID, MIN. 6 mm. HAVE BEEN MENTIONED.
Re: a question Dear friends Your comments are OK. My opinion is as followed. If you think that other parameters are important please complete this. Standards define some ranges for Minimum thickness such as 8 mm. But the important parameter that can be used for measuring the minimum thickness is ultrasonic WAVELENGTH. When plate thickness is thin in comparison with the wavelength, guided waves can propagate in the plate with a low attenuation. These waves are dispersed and can not be evaluated by common ultrasonic methods. So, if you use high frequency probes, you can use the UT for thin plates such as plates with a thickness lower than 1 mm. If you want information for a research, I recommend that you read some papers about Lamb wave or Guided wave. Best wishes Kaveh