This research investigated the residual stresses in narrow-gap API 5L X65 pipe girth welds in as-welded and after post weld heat treatment (PWHT) conditions. The PWHT included global furnace and local practices. Non-destructive neutron diffraction (ND) strain scanning was carried out on selected pipe spools and strainfree reference samples for the determination of the lattice spacing before and after PWHT. The as-welded and post-heat treatment residual stresses measured in the pipe spools were examined and compared. Experimental work also included full residual stress mapping in the weldment and through-thickness measurement at weld centre and close to the external and internal pipe surfaces. The measured profiles were compared with the recommendations given in British flaw assessment procedure BS 7910 "Guide to methods for assessing the acceptability of flaws in metallic structures" and the UK nuclear industry's R6 procedure. The design, preparation and experimental neutron diffraction measurement procedures for the determination of the strain-free lattice parameter in various configurations of reference samples and in the required directions were discussed. The variability of the lattice spacing in the reference samples was found depended on the specimen manufacture methods and thermal process. Welding residual stresses were also simulated using finite element analysis (FEA) modelling approach. The simulated thermal cycles and transient strains at specific locations were compared with the experimental readings. The residual stress profiles derived from finite element model were compared with the measurements from neutron diffraction. It was found, the measured and simulated, as-welded - residual stress profiles showed good consistency in terms of stress distribution and magnitude to reasonable extent. Measurement results also indicated that local PWHT was effective in reducing the residual stresses in the pipes to a level similar to that achieved by a global approach.

Dagligen bedömer människan sin omgivning utifrån sina fem sinnen. Då ett intryck ges från omgivningen sker en process, signaler skickas till hjärnan via nerver ifrån det sinne som stimulerats. På grund av den olika uppsättningen nervceller upplevs samma intryck skilt bland människor. I textilproduktion används visuell bedömning genom hela produktionsprocessen, från garn till färdig vara där tyget slutligen kontrolleras i sin helhet vid avsyningen. Avsyningsprocessen sker vid ett avsyningsbord där en operatör matar fram tyg på bordet. Frammatningen stoppas då fel upptäcks och de märks ut med hjälp av felkoder. Att avsyna och bedöma fel kan vara mycket svårt då uppfattningen om hur något ser ut är individuellt och således tolkas det som granskas olika. AB Ludvig Svensson har utformat uppdraget som går ut på att studera företagets bedömningsgrunder för tyg och utveckla dem för att kunna hantera svårbedömda fel. Företaget sorterar in svårbedömda fel i något de kallar en gråzon. Gråzon är oftast en benämning för ett svårdefinierat område.För att få en förståelse för var och hur fel uppstår i produktionen har observationer gjorts på företaget där hela textilprocessen studerats. Genom samtal med berörd personal och analyser av felvaror har bedömningsunderlag utvecklats. Bedömningsunderlaget går ut på att ge avsyningspersonalen så mycket information och kunskap som möjligt för en enklare bedömning. Studien har visat att gråzonen kan delas in i två delar, gråzon 1 och gråzon 2. Gråzon 1 behandlar tydliga fel där felkällan är okänd och gråzon 2 behandlar otydliga fel där den eventuella felkällan är känd. För att eliminera gråzon 1 ligger fokus på att ge avsyningspersonalen så mycket information om varan och dess processer som möjligt. Gråzon 2 kan minskas med hjälp av designbeskrivning om hur varan ska upplevas vid avsyningen. Beskrivningen placeras på ett textilt referensprov som avsynaren alltid använder vid syning av en vara.Daily man's surroundings are evaluated based on their five senses. When an impression is given from the surroundings a process starts, signals are sent to the brain via nerves from the stimulated sense. Due to the different set of neurons the same impression is experienced differently among people. In textile production visual evaluation is used throughout the entire production process, from yarn to finished product, in which the fabric finally is checked in its whole at the inspection. The inspection process occurs at an inspection table where an operator feeds the fabric on to the table. The feeding is stopped when defects are discovered which are marked by defect codes. To inspect and evaluate defects can be very difficult when the perception of how something looks is individual and therefore what is examined is interpreted differently.AB Ludvig Svensson has designed the mission that is to study the company's evaluation criteria’s for fabric and develop them to be able to deal with imponderable defects. The company sorts imponderable defects into what they call a gray zone. Gray zone is usually a term used to describe an elusive area.To gain an understanding of where and how defects occurs in the production observations have been made at the company where the whole textile process has been studied. Through conversations with concerned staff and analysis of products with defects, evaluation material has been developed. The evaluation material is meant to give the inspection staff as much information and knowledge as possible for an easier evaluation. The study has shown that the gray zone can be divided into two parts, gray zone 1 and gray zone 2. Gray zone 1 process clear defects where the defect source is unknown and gray zone 2 process unclear defects where the possible defect source is known. To eliminate gray zone 1, focus lays on providing the inspection staff with as much information about the product and its processes as possible. Gray zone 2 can be reduced with the help of a description from the designer of how the product should be experienced at the inspection. The description is placed on a fabric reference sample that the inspector always uses during the inspection process. / Program: Textilingenjörsutbildningen