| Component Type | Octagonal or oval metal ring profile for API 6A and compatible flanges | Pressure-energized metal ring profile for API 6A applications | Pressure-energized, pitch-diameter-controlled ring profile for high-pressure flanges | Typical ring-joint gasket base material; UNS S31603 | Nickel-chromium-molybdenum ring-joint gasket material; UNS N06625 |
| Primary Standard or Reference | API Specification 6A; ASME B16.20 dimensional reference where applicable | API Specification 6A; ASME B16.20 dimensional reference where applicable | API Specification 6A; ASME B16.20 dimensional reference where applicable | ASTM A182 / ASME SA-182 material requirements for forged stainless components | ASTM B446 / ASME SB-446 or an agreed equivalent specification for alloy 625 bar and ring products |
| Sealing Mechanism | Metal-to-metal line contact created by bolt load and controlled deformation | Initial contact is enhanced by internal pressure, which increases seating force | Pressure-energized sealing with controlled radial expansion in the groove | Provides corrosion-resistant metal sealing when the profile and hardness are correctly matched | Provides high-temperature and highly corrosion-resistant metal sealing in severe service |
| Common Pressure-Service Range | Commonly selected for API 6A rated systems up to approximately 10,000 psi, subject to size and flange rating | Commonly selected for API 6A rated systems up to approximately 15,000 psi, subject to size and flange rating | Commonly selected for API 6A rated systems up to approximately 20,000 psi, subject to size and flange rating | Pressure capability depends on the selected R, RX, or BX profile, dimensions, flange rating, and installation | Pressure capability depends on the selected profile, dimensions, flange rating, and installation; material alone does not determine pressure rating |
| Typical Chemical Composition | Profile designation only; final performance depends on the selected metal grade and coating | Profile designation only; final performance depends on the selected metal grade and coating | Profile designation only; final performance depends on the selected metal grade and coating | Cr 16.0–18.0%; Ni 10.0–14.0%; Mo 2.0–3.0%; low carbon grade | Ni balance; Cr 20.0–23.0%; Mo 8.0–10.0%; Nb + Ta 3.15–4.15%; Fe up to 5.0% |
| Corrosion Resistance | Determined primarily by the ring material; carbon steel and stainless options require different service controls | Determined primarily by the ring material; suitable material selection is essential for sour and chloride service | Determined primarily by the ring material; premium alloys are often used for demanding wellhead and production environments | Good general corrosion resistance and useful resistance to many chloride-free process environments | Excellent resistance to pitting, crevice corrosion, chloride stress-corrosion cracking, and many aggressive media |
| Temperature Suitability | Select according to the ring material, coating, process temperature, and API service requirements | Select according to the ring material, coating, process temperature, and API service requirements | Select according to the ring material, coating, process temperature, and API service requirements | Commonly used for moderate-to-high temperature service; verify grade, flange rating, and thermal cycling requirements | Suitable for high-temperature service; retains strong corrosion resistance and mechanical performance at elevated temperatures |
| Typical Industry Applications | Wellhead equipment, low-to-medium pressure drilling systems, valves, and pipeline connections | High-pressure wellhead equipment, valves, drilling systems, and production manifolds | High-pressure and high-integrity wellhead, Christmas tree, subsea, and production equipment | Water injection, general oil and gas service, chemical processing, and non-severe corrosive applications | Sour service, subsea equipment, offshore production, chemical processing, and high-chloride environments |
| ODM Customization Options | Custom dimensions, material grade, surface finish, plating, marking, packaging, and inspection documentation | Custom dimensions, material grade, pressure class, surface finish, plating, marking, and batch traceability | Custom dimensions, alloy selection, anti-galling treatment, identification marking, packaging, and full inspection plans | Custom profile selection, dimensional tolerances, hardness control, PMI, heat treatment records, and certificates | Custom profile selection, material certification, PMI, heat treatment, hardness control, NACE-related requirements, and traceability |
| Relative Cost Level | Low to medium | Medium | Medium to high | Medium material cost | High material cost |
| Key Buyer Verification Points | Confirm exact flange compatibility, ring number, material grade, hardness differential, dimensions, and surface condition | Confirm pressure class, groove compatibility, controlled tolerances, material traceability, and pressure-test requirements | Confirm pitch diameter, groove dimensions, pressure class, hardness requirements, coating, and installation procedure | Request heat numbers, chemical analysis, mechanical test results, PMI records, dimensional inspection, and corrosion-service suitability | Request full material certificates, PMI, heat treatment records, hardness results, corrosion-service compliance, and complete batch traceability |