High-Pressure Sanitary Clamp Fracture

Case Description

High-pressure sanitary clamps are used to hold together pressurized systems for handling and processing material for use that must remain sanitary, such as food or pharmaceutical products. In this case, equipment for solvent extraction unexpectedly released flammable gas which ignited, damaged the facility, and injured a worker. Allegedly, a single brass nut fracture occurred, causing a high-pressure sanitary clamp to disconnect release the gas.

Steps Taken:

ARCCA’s expert conducted a thorough investigation of the evidence available to determine the root cause of the failure, and examined the origin of the components involved in the failure by:
  • Reviewing the initial documentation including OSHA investigation reports and supporting documents, expert reports on the cause of the accident, invoices, technical data sheets, and the plaintiff’s product liability complaint.
  • Preforming a joint inspection and testing the evidence with experts representing each of the involved parties present.
  • An optical microscope examination of the fracture surfaces to identify the type and origin of fracture.
  • Using a Scanning Electron Microscope (SEM) for higher-magnification examination of the fracture surfaces to further narrow down the cause of fracture.
  • Preforming elemental analyses to determine various component compositions including X-ray Fluorescence Spectroscopy (XRF), Energy-Dispersive X-ray Spectroscopy (EDS), and Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES)
  • Hardness testing of various components.
  • Reviewing the incident equipment’s product manuals and use instructions.
  • Comparing different components’ compositions and properties to standard alloys.

Final Findings:

Based on inspection of the failed nut, ARCCA’s expert determined that the nut failed by brittle fracture which was predominantly intergranular with some transgranular cleavage. Possible contributing factors included the formation of lead precipitates at the grain boundaries and/or environmentally-assisted crack growth. ARCCA’s investigation revealed that the elemental composition of both the subject nut and replacement nuts found at the facility varied significantly from part to part. Neither the size of the subject nut nor its elemental composition matched the products carried by the suppliers that were defendants in the case.
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