Oil & Gas
High pressure, sour service, explosive decompression, and years between interventions — seal compound selection here is engineering, not inventory management.
Oil and gas sealing applications span the full range of severity — from low-pressure pipeline valve stem packings to wellhead connectors at 15,000 PSI with H₂S sour service requiring NACE MR0175 material compliance. The consequences of seal failure scale accordingly: a weeping flange on a process vessel is a maintenance event; a failed O-ring on a wellhead valve is a well-control incident. HNBR, FFKM, and FKM are the materials that dominate this industry because they combine hydrocarbon fluid resistance, the ability to handle H₂S and CO₂ exposure, and the thermal stability required for downhole and process temperatures. Every specification here needs to be matched to the actual service conditions — pressure class, fluid chemistry, temperature, and whether sour service certification is required.
Our Products
ELASFOR Product Line — Oil & Gas Applications
| ELASFOR Product | Oil & Gas Application |
|---|---|
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O-rings — HNBR, FKM, FFKM, NBR
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Wellhead valve bodies and connectors, BOP (blowout preventer) stack connections, Christmas tree instrument ports, pipeline valve seats, and process vessel flanges — HNBR for sour service (H₂S) per NACE MR0175; FFKM for high-temperature/high-pressure downhole applications; FKM for general oil and gas process service; all grades available in API 6A and API 6D pressure ratings |
| Wellhead flange seals, subsea connector seals, pipeline pressure vessel connections, and heat exchanger shell-and-tube gaskets — FFKM and ePTFE for sour service and high-temperature flanged connections; ePTFE joint sealant for raised-face flanges with low available bolt load; HNBR high-pressure static seals for downhole tools | |
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Pipeline flange gaskets (ring-type joint profiles and full-face flat gaskets), vessel manhole gaskets, heat exchanger cover gaskets, separating vessel access gaskets — FKM and HNBR sheet for hydrocarbon and sour service; ePTFE for corrosive produced water and chemical injection lines; CNAF for general process utilities; cut to ASME B16.20 or EN 1514 dimensions |
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Valve stem seals (chevron PTFE V-packing), gas compressor piston rod packing rings, chemical injection pump seals, and spring-energized PTFE lip seals for pump shafts on chemical treatment systems — PTFE is chemically inert to virtually all produced fluids and injection chemicals; spring-energized designs compensate for PTFE's limited elasticity in dynamic applications |
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Pipeline valve stem gland packing, process pump gland packing, and wellhead valve packing — graphite and carbon fibre braids for hydrocarbon and high-temperature service; PTFE/graphite combination packing for chemical injection and produced water service; flexible graphite packing rings for high-pressure valve glands |
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Subsea hydraulic actuator seals, pipeline pig launcher/receiver cylinder seals, wellhead control system hydraulic cylinders, and drilling rig hydraulic draw-works seals — polyurethane and FKM rod and piston seals for high-pressure hydraulic service in oil and gas environments; HNBR seals where H₂S-containing hydraulic or process fluid is present |
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Process pump shaft seals on crude oil transfer, produced water injection, and chemical injection systems — dual mechanical seals with pressurised barrier fluid (API Plan 53) for hazardous and toxic fluid services; SiC/SiC face pairs for abrasive produced fluids; single seals for low-hazard utility services per API 682 Category 1 |
Sour service applications (H₂S partial pressure ≥ 0.0003 MPa absolute) require material compliance with NACE MR0175 / ISO 15156 — not all FKM or HNBR compounds meet hardness and composition limits. Provide the H₂S concentration, temperature, and pressure class when inquiring for sour service seals and we will confirm the correct grade and available certification.
Applications
Common Sealing Applications
Wellhead & Christmas Tree Seals
Wellhead valves, gate valves, check valves, and Christmas tree assemblies operating at pressures from 2,000 PSI (API 2000) to 15,000 PSI (API 15000) with produced fluids that commonly contain H₂S, CO₂, methane, condensate, and produced water. Downhole temperatures from surface ambient to 175°C+ for deep wells. Seals at the wellhead are production-critical — a seal failure requires well shut-in, a service crew, and potential workover depending on the severity and access.
HNBR (hydrogenated nitrile) is the industry standard for sour service wellhead O-rings — excellent resistance to H₂S-containing crude oil and gas, superior explosive decompression resistance vs. standard NBR, and hardness control to meet NACE MR0175 limits (typically Shore A 90 maximum). FFKM for HPHT (high pressure/high temperature) wells where temperatures exceed 150°C and fluid chemistry is aggressive — Kalrez 6375 or Chemraz 625 are the typical grades. Confirm explosive decompression rating for all gas service applications — specify the ED test standard (ISO 23936-2) and the required pressure cycle conditions when requesting quotation.
API 6A (wellhead and Christmas tree equipment) · NACE MR0175 / ISO 15156 (sour service) · ISO 23936-2 (explosive decompression) · API 6D (pipeline valves)
Pipeline & Process Vessel Flanges
Trunk pipeline flanges, metering station piping, separator vessel nozzle connections, heat exchanger shell and tube headers, storage tank nozzle flanges, and chemical injection piping. Pipeline service pressures from Class 150 (20 bar) to Class 2500 (420 bar); fluids include crude oil, natural gas, produced water, injection chemicals (methanol, glycols, scale inhibitors), and at some facilities, H₂S-containing sour gas at elevated partial pressures.
ePTFE (expanded PTFE) is the preferred material for chemical injection flanges and produced water piping — near-universal chemical resistance, near-zero compression set, and low required bolt load make it practical for flanges that are frequently opened and re-sealed. FKM sheet for hydrocarbon service above 100°C or where ePTFE creep under high sustained bolt load is a concern. HNBR sheet gaskets for sour service where elastomeric conformability is needed and metallic ring-type joint (RTJ) gaskets are not used. Re-torque all sheet gasket flanges after first heat-up cycle — this is not optional on natural gas service.
ASME B16.20 (metallic gaskets) · ASME B16.21 (nonmetallic flat gaskets) · EN 1514-1 · API 6A · NACE MR0175 (sour service material requirements)
Subsea & Deep-Water Connectors
Subsea wellhead connectors, subsea pipeline manifold connections, subsea control module (SCM) hydraulic connections, Christmas tree ROV-operated valve seals, and riser connections from 200 m to 3,000 m water depth. The combined environment — H₂S in produced fluids, CO₂ partial pressure, hydrostatic water pressure, deep-water ambient temperature of 2–4°C, and years-long intervention intervals — defines one of the most demanding sealing environments in any industry.
HNBR is the subsea industry standard for sour service O-rings — field-proven across decades of North Sea and Gulf of Mexico subsea installations in environments with H₂S partial pressures up to 1 MPa. Explosive decompression-resistant HNBR grades (tested to ISO 23936-2 with rapid pressure cycles representative of actual well shut-in scenarios) are required for gas service. FFKM for HPHT subsea trees above 150°C — specifying Kalrez 6375 or equivalent grades tested for simultaneous high pressure, high temperature, and sour service. Confirm the specific ISO 23936-2 test parameters (pressure, temperature, number of cycles, medium) that represent your installation when requesting certification documentation.
API 6A · API 17D (subsea wellhead equipment) · NACE MR0175 / ISO 15156 · ISO 23936-2 (explosive decompression) · DNV-RP-F112
Valve Stem Seals & Gland Packing
Gate valves, globe valves, and ball valves on trunk pipelines, gathering lines, compressor station piping, wellhead production headers, and flare system headers. Valve stem packing must seal against the process pressure (from Class 150 at 20 bar to Class 2500 at 420 bar) while allowing manual or actuated stem movement, with leakage requirements increasingly governed by fugitive emission regulations (EPA Method 21, ISO 15848, TA Luft).
Graphite packing is the standard for hydrocarbon gas valve stem glands — compatible with virtually all hydrocarbons, steam, and process chemicals; self-lubricating; and capable of being repacked live under pressure on most valve designs. PTFE chevron stacks for chemical injection and produced water valves where graphite's abrasion on the stem is a concern or where FDA-grade materials are required for water treatment chemicals. For fugitive emission compliance (ISO 15848 Class B or Class A, TA Luft), specify low-emission packing sets tested and certified to the applicable standard — standard braided packing does not meet these requirements without live-load springs or specific packing designs.
API 622 (valve packing fugitive emissions testing) · ISO 15848-1 (industrial valves — measurement of fugitive emissions) · TA Luft (German clean air regulations) · EPA Method 21 · ASME B16.34
Process Pumps & Compressor Seals
Crude oil transfer pumps, produced water injection pumps, natural gas liquids (NGL) transfer pumps, gas compressor seal systems, and chemical injection metering pumps. Pump mechanical seals in oil and gas service must handle abrasive particles in produced fluids, flashing hydrocarbons near the vapour pressure limit, and sour service conditions where the secondary O-rings in the seal assembly must also meet NACE MR0175 requirements — not just the primary seal faces.
Silicon carbide/silicon carbide (SiC/SiC) face pairs are standard for oil and gas process pumps handling crude oil with abrasive sand content — SiC's extreme hardness resists the abrasive wear that quickly destroys carbon/ceramic face pairs in produced fluid service. API 682 Category 2 or Category 3 dual seal arrangements for pumps handling toxic, flammable, or environmentally regulated fluids — the pressurised barrier fluid (Plan 53A or 53B) keeps the inboard seal face lubricated and provides a containment layer for the process fluid. Specify HNBR secondary O-rings (not standard NBR) for the entire seal assembly on sour service pumps — the secondary O-ring is in direct contact with process fluid and must meet NACE hardness limits.
API 682 (mechanical seals — petroleum and gas industry) · ISO 21049 · NACE MR0175 / ISO 15156 · API 610 (centrifugal pumps for petroleum) · ISO 13709
Compliance
Governing Standards
| Standard | Scope | What It Covers for Seals |
|---|---|---|
| NACE MR0175 / ISO 15156 | Materials for sour service (H₂S-containing environments) | Material requirements for equipment used in H₂S-containing oil and gas environments — defines hardness limits (typically Rockwell C 22 max or Shore A 90 max for elastomers), approved alloy lists, and testing requirements; mandatory compliance reference for all seals in sour service |
| API 6A | Wellhead and Christmas tree equipment | Design, materials, testing, and documentation requirements for wellhead valves, connectors, and fittings; defines pressure ratings (2000–20000 PSI), temperature classes (L to V), and material classes (AA–HH) for seal selection in wellhead applications |
| API 6D | Pipeline valves | Specification for ball, plug, gate, and check valves for pipeline service; defines seat and seal requirements, pressure testing protocols, and material requirements including temperature class ratings for pipeline valve elastomeric seals |
| ISO 23936-2 | Petroleum and gas — non-metallic seals — explosive decompression | Standard test method for evaluating elastomers for explosive decompression resistance; defines test conditions (pressure, temperature, medium, number of cycles) and pass/fail criteria; the required certification for O-rings used in gas service where rapid pressure cycling occurs |
| API 682 / ISO 21049 | Mechanical seals — petroleum, petrochemical, and natural gas industry | Defines seal categories (1, 2, 3), arrangements (single, dual pressurised, dual unpressurised), and piping plans (Plan 11, 53A, 53B, etc.) for process pump mechanical seals; the primary specification reference for pump seal selection and installation in oil and gas process service |
| API 610 / ISO 13709 | Centrifugal pumps for petroleum service | Design and materials specification for process pumps in oil and gas applications; defines mechanical seal chamber dimensions and requirements that drive seal selection and API 682 arrangement applicability |
| ISO 15848-1 | Industrial valves — fugitive emissions measurement | Classification and test methods for valve packing and stem seal fugitive emission performance; defines Class A (ultra-low) and Class B (low) emission limits driving packing specification for gas service valves subject to environmental regulations |
| API 622 | Process valve fugitive emissions — packing qualification | Type testing procedure for valve packing fugitive emission performance; used to qualify packing sets for valves in EPA Method 21 and LDAR (Leak Detection and Repair) regulated service on process plants and pipeline facilities |
| ASME B16.20 | Metallic gaskets for pipe flanges | Dimensions, tolerances, and material requirements for ring-type joint (RTJ) and spiral wound gaskets for ASME B16.5 and B16.47 flanges; the reference for specifying and replacing high-pressure pipeline flange gaskets in ANSI pressure class service |
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