Glass-Lined Flange Assembly With Segmented Fire-Rated Gasket Face
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Solution Overview
Problem
Conventional glass-lined flanged fittings fail to meet the NFPA 30 standard for flammable and combustible liquids and do not pass the fire test specified in API Specification 6FB, particularly when used in conjunction with non-metal lined equipment or expansion joint fittings.
Innovation Solution
A flanged fitting design featuring a glass liner on the radially inner annular portion of the flange and a fire-rated annular inlay on the radially outer portion, combined with a dual-layer gasket comprising a liquid-tight and fire-rated seal, ensures compliance with NFPA 30 and API Specification 6FB by forming a fire-rated seal and maintaining integrity during high-temperature fire tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass liner is used to line the entire flange surface, then liquid-tight sealing is improved, but fire resistance deteriorates
Solution Approach 1:
The flange surface is segmented into two distinct zones: a radially inner annular portion lined with glass liner for liquid-tight sealing, and a radially outer annular portion left bare or fire-rated for fire resistance. This segmentation allows each zone to fulfill its specific functional requirement without compromising the other.
Solution Approach 2:
Different surface treatments are applied to different radial zones of the flange. The radially inner portion receives glass liner coating optimized for chemical resistance and sealing, while the radially outer portion maintains fire-rated properties. This local differentiation of material properties resolves the contradiction between sealing and fire resistance.
2Device complexity
If a conventional single-layer gasket is used, then device complexity is reduced, but the ability to provide both liquid-tight and fire-rated seals deteriorates
Solution Approach 1:
The gasket is segmented into two distinct annular layers: an inner layer positioned against the glass-lined flange surface to provide liquid-tight sealing, and an outer layer positioned against the fire-rated flange surface to provide fire-rated sealing. This segmentation enables the single gasket component to deliver dual sealing functions.
Solution Approach 2:
The gasket employs a composite structure with two different material layers, each selected for its specific sealing properties. The inner layer material is optimized for chemical compatibility and sealing against glass liner, while the outer layer material is optimized for fire resistance and sealing against fire-rated surfaces.
Data Source
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AI summary
A flanged fitting includes an annular fitting flange having an annular end face. A glass liner lines a radially inner annular portion of the annular end face of the annular fitting flange. A radially outer annular portion of the annular end face of the annular fitting flange is free from the glass liner. The radially inner annular portion and the radially outer annular portion of the annular end face of the annular fitting flange define an annular gasket abutment face configured to seat a gasket thereon. An annular gasket includes an annular gasket layer. The annular gasket layer includes a radially inner annular gasket segment including a first material suitable for forming a liquid-tight seal with an opposing flange. A radially outer annular gasket segment surrounds the radially inner annular gasket segment. The radially outer annular gasket segment is fire-rated for forming a fire-rated seal with the opposing flange.