Gasket Design for Alkylation Units & Other Possible Dangerous Liquid Media

The design and testing of gaskets for severe, possibly life threatening, liquid media, like hydrofluoric acid, is critical and difficult. This paper shows the relationship between basic gasket stress calculations, of applied load over the gasket sealing area, actual gasket stress test results, and dye penetrant test results. The gasket designs evaluated will be from across the industry and follow the typical design of having expanded PTFE (ePTFE) as the inner sealing element for the harsh media and a redundant flexible graphite sealing element that will seal the media as well as give an expected fire test rating. The gaskets tested had different structural designs for sealing the media as well as providing corrosive protection for the clamping flanges. There was both supported and unsupported ePTFE sealing elements. Some designs are new, and one has been in service for years. The basic calculations typically used to determine adequate gasket stress showed that all the gaskets should seal effectively. The question is: Would they all equally help protect the flange face from corrosive damage? The data from the actual applied gasket stress correlates nearly perfectly to the dye penetrant results but varies from expected stress distribution of the typical gasket stress calculation. The paper will cover the theoretical calculation approach, the test methodology for the actual applied gasket stress, the methods for ensuring applicable dye penetrant testing and comparing the results to each other. The results show that under equal clamping loads, the different structural designs directly impact the ability for fluid to penetrate the ePTFE section of the gaskets.

A novel AE algorithm-based approach for the detection of cracks in spot welding in view of on-line monitoring: case study

The detection of cracks in spot welding is a major issue especially on-line. This paper deals with this topic using acoustic emission monitoring. It proposes an approach based on Shannon entropy with a novel criterion that allows increasing the detection sensitivity. A data-based model is built, coded and then applied on acoustic emission signals. The obtained crack detection results are satisfactory. The cracks are revealed using fluorescent dye penetrant, which enables validating the method. A flowchart of whole the proposed approach is described so that practitioners can benefit from the authors experience, towards successful implementation in laboratory as well as in production-line. The current approach is applied on resistance spot welding as a case of study, but it could be applicable in non-stationary environment such as other kinds of spot welding, and more hopefully for other manufacturing processes.

Oxy Acetylene Welding Analysis for Plastic Welding of Thermoplastic Polymer Materials

Plastic welding technique is a technique of gluing to workpieces, especially plastic materials. The aim of this research was to join the thermoplastic polymer material using an acetylene oxy welding. The connection method is by melting the electrodes on the workpiece so that the electrodes can fuse to the parent material. The materials used are Polyethylene (PE), Polyvinyl chloride (PVC) and Polypropylene (PP) plastic sheets with the appropriate electrodes from their respective parents. After going through the welding process, the weld results are tested using a dye penetrant. The best results from the dye penetrant are then tested for hardness

Porosity Defect Analysis in ST 37 Steel Welding Joints Using the Dye Penetrant Method

The procedures in the world of welding all look simple, but all welding that looks simple must have extensive knowledge in accordance with the definition of welding. This welding is a permanent connection technique, when the welding process takes place the results do not always meet the quality standards that have been determined. The cause of the welding results that do not meet the quality standards in the form of dirt on the material when before welding and so forth. The purpose of this study is that the specimen specimens are accepted according to the welding institute's standard acceptance criteria (TWI) This research uses st 37 steel by using SMAW welding electrodes LB 52U (E 7016) diameter 2.6mm for root, and LB 52U (E 7016) diameter 3.2 for fillers and caping with welding position 1G. Testing of welding results is carried out by the non destructive test of the dye penetrant method whose inspection results are determined based on the standard ASME. The results of this test study discontinuity in the form of porosity on the surface of the welding results in specimen 1, namely material contaminated by dirt, there are porosity defects scattered with a length of 6mm and porosity of 10mm so based on the standard TWI both test specimens were declared rejected, and in specimen 2, material that was not contaminated with impurities, there were porosity defects of 2mm and 2.5mm so that according to the standards of the two specimens the test was accepted. For the results of welding defects that are rejected can still be corrected by linking to the defects that, and can be done welding again.