The capability of making a smooth, crevice-free inner weld bead on a repeatable basis, has led, over the past decade, to orbital welding becoming the preferred joining technology for biopharmaceutical process piping.The expanding biopharmaceutical industry in the USA has placed an increasing emphasis on quality standards and documentation in order to expedite the approval process for new therapeutic products by the FDA (United States Food and Drug Administration).Manual welding may be used, with the owner’s permission, only when using an orbital weld head would create a deadleg. In ASME BPE-97 (Table SD-1) a deadleg (L/D) of 2:1 is considered to be an achievable target value for bioprocessing systems where L is the length of the extension measured from the OD of the primary pipe, and D is the I. Where they exist, they should be designed so that it is possible to flush through them. Left: manual weld taken from an operating pharmaceutical plant.A deadleg is defined as a pocket, tee, or extension from a primary piping run that exceeds a defined number of pipe diameters from the I. Note lack of penetration, misalignment, discoloration, crevices and protruding material on the product contact surface.The ASME published the ASME Bioprocessing Equipment Standard (BPE-97) in 1997. Stainless steel piping system installed with orbital welding at a UK pharmaceutical installation. Welder tests require six linear inches of weld or multiple coupons, but not more than four.Tank bottoms and piping are sloped for drainability. It should be noted that hot WFI water, circulated at temperatures above 40ºC, may be classified as category M fluid service in ASME B31.3, which includes substances which will do irreparable harm in case of a piping system failure in which the contained process fluid comes into contact with human tissue.The ASME B31.3 Process Piping Code gives to the owner the ultimate responsibility for documenting to the FDA that the critical piping systems have been manufactured, fabricated, and installed according to the CGMPs.
Special emphasis was placed on the quality of weld surfaces once the required strength was present. Welders and welding operators may be qualified by making acceptable test welds and documenting test results on Form QW-484*.The FDA is very non-specific about how a critical piping system should be constructed, but relies upon the requirements detailed in the ASME B31.3 Process Piping Code and the ASME Bioprocessing Equipment Standard (BPE-97).It should be noted that a code is required by law, while a standard provides generally accepted industry practices.Of these documents, the most significant is 21 CFR (Code of Federal Regulations) B211 which specifies how the various components in pharmaceutical manufacturing facilities are to be constructed.21 CFR B211.65 Subpart D states: (a) Equipment shall be constructed so that surfaces that contact components, in-process materials, or drug products shall not be reactive, additive or absorptive so as to alter the safety, identity, strength, quality, or purity of the drug product beyond the official or other established requirements.