Expansion Joint Fitting With Fire-Rated Seal for Flammable Liquids
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Solution Overview
Problem
Conventional flanged fittings for flammable and combustible liquids fail to meet the NFPA 30 standard and API Specification 6FB fire test requirements, particularly when used in non-metal lined equipment or expansion joint assemblies.
Innovation Solution
A flange joint assembly comprising a fire-rated flanged fitting with an internal liner, an annular flange extension, and an annular gasket, which includes a nickel alloy or reactive metal inlay and fluoropolymer gasket segments, forming a liquid-tight and fire-rated seal that withstands high temperatures and prevents fire spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional glass-lined flanged fittings are used for flammable liquids, then corrosion resistance is improved, but fire safety fails to meet NFPA 30 and API 6FB standards
Solution Approach 1:
The flanged fitting employs a composite structure combining a metal substrate (carbon steel, nickel alloy, or reactive metal) with a glass lining layer. The glass lining provides corrosion resistance for flammable liquid service, while the metal substrate provides fire safety and structural strength, allowing the assembly to meet both NFPA 30 and API 6FB fire test standards
Solution Approach 2:
The glass lining is nested within the metal substrate, creating a layered structure where the inner glass layer provides chemical resistance and the outer metal layer provides fire resistance and mechanical strength, resolving the contradiction between corrosion protection and fire safety
2Adaptability or versatility
If conventional expansion joint fittings are used with non-metal lined equipment, then flexibility and expansion capability are improved, but fire safety fails to meet NFPA 30 standards
Solution Approach 1:
The expansion joint fitting uses a composite construction with metal end sections (flanges) that meet fire safety standards, connected to a flexible element (bellows or corrugated section) that provides expansion capability. The metal flanged ends ensure compliance with NFPA 30 while the flexible intermediate section provides the required adaptability
Solution Approach 2:
The expansion joint is segmented into distinct functional zones: rigid metal flanged ends for fire safety and connection, and a flexible intermediate section for expansion accommodation, allowing each segment to fulfill its specific function without compromising overall performance
Data Source
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AI summary
An expansion joint fitting for conveying liquid includes a radially inner bellows defining a liquid-conveying passage for conveying liquid between the first and second longitudinal ends of the expansion joint fitting. A radially outer bellows is disposed radially outward from and extending around the radially inner bellows. An annular plenum is defined between the radially inner bellows and the radially outer bellows.