Welding checking

There has been a rapid growth in use of isotopes in medical research, medical therapy, smoke detectors, static eliminators, sealed sources for a variety of purposes including weld checks, geophysical examinations, etc. Most of these wastes will be buried in low level waste disposal facilities. 

No firm conclusion should be drawn from the above data, through the observed pattern deserves attention. The AE activity observed on the SH header can originate from the weld, but could be due to other causes, namely to the settlement of the hanger. Ultrasonic inspection of the weld at regular intervals checks whether any sizeable change in NDT response from the weld has taken place. 

Besides large-diameter pipes, ultrasonic testing is used for checking the welded joints of drill bits, components of wind-driven electric plants, welded joints of light alloys and non-metallic materials, for an integrated inspection of various objects. A range of training aids developed at the Institute allows the operators to be trained effectively. 

Agreement on the NDE plan will be dependent on the extent and relevance of theschedule. Under the amendments proposed to the Rules Surveyors will check that structurally significant welds are included in the shipyard s quality control programme. When agreement has been reached the Surveyor will endorse the plan. 

Weld inspection duties of personnel responsible for judging the quahty of welding with regard to specifications have been treated (15). Some of these duties involve the visual inspection of welds to determine if they are of the proper size, location, and type and are free of defects. Specifications of materials used must be checked, as must equipment and procedures. 

Tlie indi ddual cells are assembled into batteries after a leakage test to check for faulty welding joints in steel containers or cracks and improper seals in the plastic encased cells. Cells that are to be delivered without electroltye are emptied after the fomiation cycles. Tlie steel-cased cells hav e to be separated by mechanical means to prevent intercell shorts and are often assembled into wooden crates. Tlie cells in plastic cases can be cemented together or strapped with tape. 

Rules for the welded fabrication of pressure vessels cover welding processes, manufacturer s record keeping on welding procedures, welder qualification, cleaning, fit-up alignment tolerances, and repair of weld defects. Procedures for postweld heat treatment are detailed. Checking the procedures and welders and radiographic and ultrasonic examination of welded joints are covered. 

The sheet may also be inspected for the quality of welding and checked for pin-holes by a weld-hole detector before it is finally cut into lengths or wound onto rolls. 

We have seen that welds can be very weak in a fatigue situation, and we would be wise to check that the modified weld in Fig. 28.7 is adequate for the job. Although it is difficult to spot immediately, the weld is in fact subjected to large bending stresses (Fig. 28.8). These can be calculated as follows. 

Increase shaft diameter and decrease end plate. thickness Increases / and decreases t in eqn. 28.10. Would need 250 mm diameter shaft + 1 5 mm thick end plate very heavy and expensive. Would still need to check plate-shell weld. 

If the control valve size is critical to the overpressure protection of the downstream equipment, and must not be increased, then this is clearly noted in all relevant documentation (specification sheets, flow diagram, operating manual, etc.,) and a warning notice plate is welded to the valve body. In such cases, an actual check of the valve installed or purchased should be made during the startup review. 

Instructions for erection and detailed welding specifications with recommendations for checking of site work,... 

Many companies now insist that if use of the wrong grade of steel can affect the integrity of the plant, all steel must be checked for composition before use. This applies to flanges, bolts, welding rods, etc., as well as the raw pipe. Steel can be analyzed easily with a spectrographic analyzer. Other failures caused by the use of the wrong construction material are described in Section 16.1. 

In the Sundyne Canned Motor design, the entire outside of the motor is enclosed in a secondary leakage containment shell or can. Primary leakage protection is provided by corrosion resistant liners which are seal welded and 100% leak checked to assure that pumped fluid does not contact the stator windings or rotor core. There is no shaft protrusion to seal and thus no seals to leak. 

Check freshly blasted surface for steel imperfections, laminations, weld spatter, etc. and ensure that any necessary metal dressing is carried out. 

It should be noted that swarf from a zirconium-titanium alloy containing approximately 50% by weight of each element is prone to pyrophoricity in air. It has also been reported that when zirconium is welded to titanium, the welded zone is much more sensitive to corrosion than either of the parent metals. If, therefore, it is proposed to use my construction in which zirconium is welded to titanium, caution should be observed in the machining of welds, and the corrosion behaviour of the weld should be checked by prior testing in the environment with which the construction will be employed. 

Brown has pointed out that Du Pont use evaluation tests for (a-) as-received unstabilised alloys containing more than 0-03% C to check the effectiveness of the final heat treatment and (b) stabilised or special low-carbon grades after a sensitising treatment (1 h at 677°C) to determine whether susceptibility might develop during a subsequent welding operation. 

The Standards, Measurements and Testing Programme of the European Commission launched a few years ago a project dealing with the development and, ultimately, the production of air filters realistically exposed to welding dust occurring during stainless steel welding (Christensen et al. 1999). This project resulted in the production and certification of a batch of 1100 filters for the Cr (VI) content (40.16 0.60 pg/g dust) (CRM 545). In addition, the total leachable Cr content ( 39.37 1.30 pg/g dust) was certified as a means to check for total Cr recovery. 

The soundness of welds is checked by visual inspection and by non-destructive testing (radiography). 

Troyan13 suggests that all pumps, compressors, turbines, and other equipment should be checked internally before they are turned on. He notes that such an inspection of a large gas compressor revealed rust and scale from nearby pipes, a welding rod, and a small pipe wrench within the cylinder itself. Starting up the compressor before these items were removed could have done enough damage that whole sections would need replacement. This could have delayed the startup for weeks or even months. 

A 2-ft-diameter float was fabricated using stainless steel and welded seam construction. Pipefitters were given the job of checking the welds for leaks. They were instructed to use 5 psi of air pressure and a soap solution to identify the leaks. 

Integrity Assurances - When first installed piping systems will be checked for leakages at weld joints and flange connections. Weld joints are usually verified by NDT radioactive means (i.e., x-ray) or die penetrants. 

Preheat temperature shall be checked by use of temperature-indicating crayons, thermocouple pyrometers, or other suitable means to ensure that the temperature specified in the WPS is obtained prior to and maintained during welding. 

Class 150 Corrosion Resistant Gate, Globe, Angle and Check Valves With Flanged and Butt Weld Ends... 

Check Valves Flanged, Lug, Wafer and Butt-welding... 

Prior to welding in or around a structure or area containing gas facilities, a thorough check shall be made to determine the possible presence of a combustible gas mixture. Welding shall begin only when safe conditions are indicated. 

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