Testing you can rely on

Rotech has many years’ experience in fastener testing and fastener failure investigations and are fully equipped to meet your specific needs and requirements within the demanding ‘high end’ quality fastener sector. Rotech is a UKAS accredited metallurgical test laboratory to BS EN ISO 17025 - see www.UKAS.com for our Schedule of Accreditation. We have two laboratory locations in the Midlands; at Wednesbury (principal laboratory) and Aldridge (weld testing laboratory)

One of our particular areas of expertise is in testing full size (i.e. unmachined) as well as tests on machined test pieces. The latter may be prepared from either sacrificial fasteners or ‘overs’. Feedstock material in bar form for subsequent use in the manufacturing of fasteners whether by cold heading, cold or hot upset forging, thread rolling or bright turned/machined finishes are tested. Fastener failure investigations are another important aspect of our work which often includes the use of our own Scanning Electron Microscope (SEM) equipped with EDS (EDAX). Rotech’s experience can help identify hydrogen embrittlement using the SEM. 

We test fasteners in carbon, low alloy, boron and stainless steels including duplex/super duplex, alloy 625, 718, 825, nickel aluminium bronzes, Monels, Inconels, Waspalloy and titanium alloys.

The Principle Fastener Product and Test Specifications we work to are ASTM A193,
 ASTM A194, BS EN ISO 3506-1, BS EN ISO 3506-2, BS EN SO 898-1, BS EN SO 898-2, ASTM F606/M, ASTM A962, ASTM F738, ASTM A370 and BS EN ISO 898-6

As well as testing to National/International Standards, we test to well-known company standards including Aker, VGS, Wellstream, Statoil, FMC, Clyde Union, One Subsea, DEF Stan, NES and others.

Fastener mechanical tests include proof load of bolts and nuts, wedge tests for head soundness, tensile test (on full size or machined samples), proof/yield stress, total elongation, reduction in area and standard or micro hardness (surface and core). We also perform torque tests (not UKAS accredited). The 24-hour hardness test including heat treatment (the heat treatment is not UKAS accredited) on nuts to ASTM A194 is routinely performed. Metallurgical tests on fasteners are increasingly more important and include decarburisation/carburisation tests, microstructural assessment including phase analysis, banding, segregation and the use of micro hardness to determine phase hardness e.g. martensite, ferrite, bainite etc.

Longitudinal sectioning and macro etching is carried out to delineate forging flow lines at the bolt head-shank interface and helps reveal structural integrity along the bolt length from head to shank end.

Chemical analysis of fasteners and/or starting material is clearly of fundamental importance-if the start material or semi-finished fastener bears the right chemistry, there is every chance that optimum subsequent downstream processing will result in specification compliance. 

Elevated temperate tensile testing and fastener surface testing can be of great importance depending on the end use application. We can perform elevated temperature tensile testing on machined fastener feed stock or machined fasteners to ASTM E21 and BS EN SO 6892-2. Any inorganic coating (e.g. plating, galvanising, sherardising)  or organic coating (e.g. painting, plastic coating, Xylan, Dacromet coating) can be salt spray tested to ASM B117/BS EN SO 9277 and we can also offer plating/coating thickness measuring to BS EN SO 1463, BS EN 1254 and coating mass determination to BS EN 10346, 10152 & 12329 (withdrawn).

Finally, we can test fastener surfaces for the presence of hexavalent chromium (Cr6/CrVI) on suspect or designed chromate treated surfaces.


For further information, please download our Fasteners Data Sheet PDF below:

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