Reference thread378-96151
RTJ gaskets should never be re-used. After being compressed by the flanges, the gasket will have experienced cold work hardening, deformed to a new geometry that may not comply with the tolerances of a new gasket, etc.
The use of RTJ flange/gasket comes from API 14E "Recommended Practice for Design
and Installation of Offshore Production Platform Piping Systems" (reaffirmed 2013).
"4.5 Flanges.
a. General. Welding neck flanges should be used for piping 2 inch and larger. Slip-on flanges are not generally recommended. ANSI type flanges, manufactured in conformance with ANSI B16.5, are used in most applications. API type flanges, manufactured according to API Spec 6A, are used primarily near the wellhead.
1) ANSI flanges are supplied in raised face (RF) and ring-type joint (RTJ). RF flanges offer increased
ease of maintenance and equipment replacement over RTJ. RTJ flanges are commonly used in higher
pressure service of ANSI 900 and above and may also be used for ANSI 600 in piping systems subject
to vibrating service. RTJ flanges should also be considered for services with special temperature or
hazard problems. When RTJ flanges are used, the piping configuration should be designed to allow
component removal since additional flexibility is required to remove the ring gasket. Materials for ANSI
flanges are normally manufactured in accordance with ASTM A-105. Flanges manufactured in
accordance with ASTM A-181 may be suitable for certain noncritical services, e.g., water or atmospheric drains."
RTJ gaskets should never be re-used. After being compressed by the flanges, the gasket will have experienced cold work hardening, deformed to a new geometry that may not comply with the tolerances of a new gasket, etc.
The use of RTJ flange/gasket comes from API 14E "Recommended Practice for Design
and Installation of Offshore Production Platform Piping Systems" (reaffirmed 2013).
"4.5 Flanges.
a. General. Welding neck flanges should be used for piping 2 inch and larger. Slip-on flanges are not generally recommended. ANSI type flanges, manufactured in conformance with ANSI B16.5, are used in most applications. API type flanges, manufactured according to API Spec 6A, are used primarily near the wellhead.
1) ANSI flanges are supplied in raised face (RF) and ring-type joint (RTJ). RF flanges offer increased
ease of maintenance and equipment replacement over RTJ. RTJ flanges are commonly used in higher
pressure service of ANSI 900 and above and may also be used for ANSI 600 in piping systems subject
to vibrating service. RTJ flanges should also be considered for services with special temperature or
hazard problems. When RTJ flanges are used, the piping configuration should be designed to allow
component removal since additional flexibility is required to remove the ring gasket. Materials for ANSI
flanges are normally manufactured in accordance with ASTM A-105. Flanges manufactured in
accordance with ASTM A-181 may be suitable for certain noncritical services, e.g., water or atmospheric drains."
