Thickness testing

There are no classification requirements for routine NDE beyond thickness testing and visual inspection except for repairs, modifications or where service history has identified a specific problem in which case the Surveyors will request NDE at the same locations in similar ships. Under circumstances where visual inspection has found evidence of fatigue cracking the Surveyor can also call for NDE to assess the full extent... 

Reference 38 is a good guide to the selection of plate thickness test methods. Test methods may vary with the purity and electrochemical activity of the deposit. Metals deposited from commercial plating solutions are seldom pure. For example, zinc deposits from the three commonly used baths, ie, cyanide, chloride, and zincate, vary significantly in purity and activity (39). Standard ASTM test methods for determining plate thickness are... 

Perform periodic thickness testing of metal pipe wall... 

Sentinel holes are used as a simple form of thickness testing. A small hole of about I - 6 mm diameter is drilled from the outer wall of the piece of equipment to within a distance from the inner wall (in contact with the corrodent) equal to the corrosion allowance on the equipment (Fig. 9.11). The technique has been used even in cases where the corrodent spontaneously ignites on contact with the atmosphere. The philosophy is that it is better to have a little fire than a big one which would follow a major leak from corrosion through the wall. When the sentinel hole begins to weep fluid a tapered plug is hammered into the hole and remedial maintenance planned. Siting the sentinel holes is somewhat speculative although erosion at the outside of a pipe bend is often monitored in this way. 

Table 8-6 Guidelines for nominal TP mold shrinkage rates per ASTM Yt Yz in. thick test specimens...

Electrodeposits, properties of, 24 749-750 Electrodeposit thickness tests, 9 789 Electrodes AFC, 12 216 carbon, 12 752-758 defined, 3 408-409 DMFC, 12 214... 

Creep testing of weld joints to determine weld joint strength reduction factors should be full thickness crossweld specimens with test durations of at least 1 000 h. Full thickness tests shall be used unless the designer otherwise considers effects such as stress redistribution across the weld. 

Peled ef al. [177] also designed a novel MEA in order to improve the water back diffusion from fhe cathode to the anode side. They used a liquid-water barrier layer (LWBL), which consisted of a paste, made out of PTFE and carbon black particles, fhat was inserted in the pores of fhe CFP to form a layer inside fhe paper. Up to seven layers were necessary in order to achieve a uniform layer of 20-50 pm in thickness. Testing showed that the LWBL on the cathode DL creates a hydraulic pressure that forces (or pushes) the water back from fhe cafhode toward the anode, thus improving the cell s water management at different operating conditions. 

Fig 1 Minimum Failure thickness Test Assembly (from Ref 4)... 

It is generally assumed that humidity is not important in most rubber tests and, hence, conditioning in an atmosphere with control of temperature only is usually specified. However, control of humidity is considered necessary in certain cases, for example testing latex rubber and electrical tests. In many instances the 16h minimum conditioning period will not be sufficient for equilibrium to have been reached, especially with relatively thick test pieces. Hence, all that this conditioning can hope to achieve is to bring test pieces having similar dimensions into more nearly comparable conditions than they would otherwise be. To reach complete moisture equilibrium would in many cases take several days and for thicker test pieces probably weeks. 

The Charpy V-notch energy needed to arrest ductile fracture as a function of stress level for API X6G and X70 material in a 30, 36, and 42 in. (760, 915, and 1,065 mm) diameter pipe calculated from this equation is shown graphically in Figure 5.21 (A = 0.1237). The limitation of the Charpy V-notch test is that it is not a full thickness test, whereas the DWTT is. This means in thicknesses more than in., compensation in the form of increased energy absorption requirements is often specified for thick pipe. 

A typical H nmr sample is 0.3 to 0.5 mL of a 10-20% solution of a nonviscous liquid or a solid in a proton-free solvent contained in a 5-mm dia. glass tube. The sample tube must be of uniform outside and inside diameter with uniform wall thickness. Test a sample tube by rolling it down a very slightly inclined piece of plate glass. Reject all tubes that roll unevenly. 

Items such as material storage, handling and application, surface preparation, mil thickness tests, environmental conditions, surface defects in the coating film and coating adhesion are all checked and recorded. Inspectors have the authority to halt work not being performed properly, and they can reject completed work that does not meet the requirements of the specification. 

With Hot-Box dehydration, one inch thick test samples are dehydrated completely in 50 seconds by contact with hot, >230 C, metal plattens In this process the sand is heated by conduction so the rate of dehydration varies with the thickness of the sand body The Hot-Box process is inefficient since there are significant energy losses by radiation from the hot metal patterns however, Hot-Box equipment is readily available in the casting industry ( ) ... 

There are currently no standards tests for measuring the thermal expansion of plastics in ISO or in BS 2782. In ASTM, test method D696 [124] uses a relatively thick test piece, which is placed in a chamber whose temperature can be controlled. This is shown schematically in Fig. 23. The expansion of the sample is transmitted to a remote dial gauge via a quartz rod that has a very low expansion coefficient. This same technique is applied in modern thermomechanical analyzers (TMA). but the dial gauge is replaced by linear displacement transducers or other electronic devices capable of detecting smaller dimensional changes. In turn this allows thinner specimens to be tested and permits wider temperature ranges to be examined. There are developments wnthin the ISO to provide a standard for these types of instruments. 

The compact tension and bend specimens were limited in thickness by the available plate. These plate thicknesses tested are near the maximum used or contemplated for use in LNG service. 

Initiation Value J PropagatiOTi Value Tj Specimen Thickness Test Speed [mm min ] ... 

The characteristics of the dependency of injection-molded NCH products on layer thickness have been investigated and reported [17]. An investigation of 0.5, 0.75, 1.0 and 2.0 mm-thick test specimens revealed that the thicker the product, the lower the elastic modulus under tension becomes. 

APH air preheater shell leaks (WHRB exit gases on shell side) Pollution in plant area APH construction as per ASME Sec VIII and statutory regulations Regular inspection shell thickness testing, pressure tests must be done. 

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