One of the many specializations Patriot Bolt holds is the ability to produce ASTM B7M fasteners with exact conformance to the specification and with complete in-house control. ASTM A193 requires the manufacturer to temper “after all machining, threading, or cutting is completed” making this a difficult product to provide with 100% specification conformance in conjunction with a same day/one day lead time. Though the specification is clear and unequivocal, it is a widespread practice to cut this material from a threaded bar which has been tempered already. The improper act of cutting this from threaded bar into the exact length can potentially add unnecessary stresses into the component making it more susceptible to corrosion and embrittlement in certain atmospheres. This is why the ASTM specification is clear that all of these stress inducing operations are done prior to final tempering process on conversion to B7M.
Unless this threaded bar is tempered again after cutting (which would be terribly costly and inefficient), the material would not comply with the ASTM requirement. Often you will see a shiny cut end on the end of a stud bolt which will indicate that the fastener has not been properly manufactured since the tempering process discolors the entire component equally.
In addition to the strict tempering requirements, there is also a requirement to 100% hardness test all components. This is another aspect that impacts delivery of materials in a short time frame. At Patriot Bolt, a calibrated and surveyed furnace with current certifications is operated in house to heat treat/temper standard ASTM B7 material and allows us to offer a product that conforms strictly to ASTM B7M specification requirement in the fastest time frame available.
Patriot Bolt is an ISO 9001:2015 accredited organization and maintains an updated record of calibration for both the furnace and hardness testing equipment. This is all supported by detailed procedures available for review by our customers. Furnace records can be provided for each batch of material and are kept on file with material test reports which can accompany each product shipment.
B7M is a popular material used in upstream oil and gas when the application has the potential to be exposed to sour gas or hydrogen sulfide where there may be concern of hydrogen embrittlement and/or sulfide stress corrosion (SSC). It is also used commonly in downstream applications such as alkylation units that process hydrofluoric acid. The tempering operation has the effect of reducing the hardness, tensile and strength of the material allowing it to be more ductile, thereby decreasing the brittleness of the material.
Contact Patriot Bolt to learn more about how we can add value to your supply chain with in-house ASTM B7M capability.