API RP 572 2001 pdf free download

API RP 572 2001 pdf free download.Inspection of Pressure Vessels (Towers, Drums, Reactors, Heat Exchangers, and Condensers).
10.8 TESTING 10.8.1 Hammer Testing In hammer testing, an inspector’s hammer is used to sup- plement visual inspection. The hammer is used to do the fol- lowing jobs: a. To locate thin sections in vessel walls, heads, and the like. b. To check tightness of rivets, bolts, brackets, and the like. c. To check for cracks in metallic linings. d. To check for lack of bond in concrete or refractory linings. e. To remove scale accumulations for spot inspection. The hammer is used for these jobs by lightly striking or tapping the object being inspected and observing the sound, feel, and indentation resulting from the blow. The proper striking force to be used for the various jobs can be learned only through experience. Hammer testing is used much less today than previously. It is not recommended to hammer test objects under pressure. Also, piping upstream of a catalyst bed should not be hammered, as hammering could dislodge scale or debris and cause plugging. 10.8.2 Pressure and Vacuum Testing When a pressure vessel is fabricated, it is tested for integ- rity and tightness in accordance with the standard or con- struction code to which it was built. (In addition to integrity and tightness, the pressure test can also result in beneficial stress redistribution at defects.) These methods of testing may also be used to subsequently inspect for leaks and to check repair work. When major repair work such as replacing a head, a large nozzle, or a section of the shell plate is per- formed, the vessel should be tested as if it were just installed. In certain circumstances, the applicable construction code requirements for inspection of vessels in service also require periodic pressure testing, even though no repair work has been necessary. For code rules concerning tests of vessels in service, see API 510 and NB-23. The ASME Code, although a new vessel fabrication code, may be followed in principle in many cases.
10.8.3 Testing Exchangers When an exchanger is removed from service, it is often desirable to apply a test to either the shell side or the tube side before dismantling. A leak may be detected by observation at a drain point, such as at a disconnected lower nozzle or an open bleeder. Usually, the test must be run for some time before a small leak will show up. If the exchanger leaks, it is then partially dismantled and the test reapplied. For example, when testing a floating-head exchanger with the pressure in the tubes, removal of the shell cover will reveal the source if the leak is in the gasket, stay bolts, or tube rolls at the floating head. This test will not normally distinguish between tube roll leaks at the stationary tube sheet and those at penetrated tube walls, as these parts are not visible while the tube bundle is in the shell. A shell test applied to a floating-head exchanger with the channel cover off will reveal leaking tube rolls at the stationary tube sheet, but will not clearly identify the source of leakage at floating tubesheet rolls or floating head gasket leaks. In most cases, exchangers that do not use a floating head are so constructed that a shell side test applied to the partially dismantled exchanger will enable individual detec- tion of leaking tubes and their plugging. Also, leaking tube rolls at either end can be detected and rerolled. Exchangers with floating heads do not permit individual detection of leak- ing tubes or access to both ends of tube during a shell side test. A test ring is sometimes used for these exchanger. This is a device that temporarily converts the arrangement of the partially dismantled exchanger into a dual fixed tube-sheet arrangement. In some cases, leak testing is performed at each down- time. Tube condition assessment can also be performed using scanning detection tools. The range of tools available includes eddy current, remote field eddy current, magnetic flux, laser and ultrasonic test equipment.