In-situ Metallurgy evaluation – often referred to as field Replication of metals – allows a very comprehensive evaluation of the components microstructure, analysis of which can determine the current strength, toughness and overall integrity of the material. This non-destructive inspection technique will also identify the presence of defects, allow crack evaluation and find other properties of interest.
Field preparation of replica location and the etching process employed will be determined by the type of material being evaluated. The practice of field replication has been extensively relied on by several industrial sectors (power generation, petrochemical and chemical) for the past number of decades to determine accurate material condition. This supports remaining life predictions which in turn allows proactive planning for plant equipment replacement.
Some common industry identified processes that regularly employ field replication for assessment are Creep damage (High Energy Piping Systems & Boiler Tubes) Sigma Phase evaluation in Duplex fittings, Grain Size calculations for material identification and analysis of cracks for determination of recent activity, intergranular corrosion or transgranular fatigue. These examinations are outlined by ASTM E 1351 as the Standard Practice for Production and Evaluation of Field Metallographic Replicas.
ANS Experienced Field Services Team
Here at Advanced NDT Solutions we have a very experienced team that have a diverse knowledge of the different materials associated with supporting projects in the Power; Petrochemical; Pharmaceutical and Chemical sectors both onshore and offshore locations globally. We understand the importance of preplanning and educating our clients on site requirements with regards to the use of chemicals, grinding, polishing and often confined space locations. All of our team members are trained in abrasive tools; confined space; hazardous material handling and we work with safety as a priority. All replications kits contain complete MSDS binders for all materials being used along with method statements and procedures for the safe performance of this inspection technique.
Field Metallurgy Replication has become the normal practice during all plant outages over the last number of decades to evaluate Boiler tubes/stubs and welds located in High Energy Piping systems that have the high potential for creep damage. This delivers the confidence for operators to decide continued service for critical plant equipment.
Choosing locations for replica sites normally is established from specific plant history but generally follows the standard rules for the different components inspected. Hardness testing is often performed in conjunction with field replication and may help in selection of suspect locations.
Tubes (Location on extrados bend)
- Header Stubs (One replica each side of stub)
- Butt Welds ( 3 locations 180° apart)
- Large Bends ( 7 Locations 3 Extrados, 2 intrados and two sides at centre)
The process of acquiring replicas in the field requires initial grinding/blending of material to remove carburization layer and local weld cap removal; then a graduated level of sanding grits (40-1200) prior to final polishing steps. Once the location is prepared the site is then etched with the appropriate chemical and acetate applied to replicate microstructure. Our technicians will evaluate replica location directly on component for preliminary evaluation and then perform detailed analysis under desktop microscope during final reporting by our metallurgist. All replicas are photographed at different magnifications (200x; 400x & 1000x) and incorporated into reports. Where clients decide to do on going In Service Inspection (ISI) programs databases for monitoring growth and locations of replicas can be developed and web based report portal access is available.
Advanced NDT Solutions personnel were involved in the large scale evaluation of Duplex Fittings installed on offshore installations in the Norwegian Sector to determine the presence of Sigma Phase. Our team members evaluated hundreds of fittings offshore during normal production and allowed for fittings with damage to be replaced on a planned process