Gaskets &
Fasteners
Supplier India
ASME B16.20 · ASME B16.21 · API 6A certified spiral wound, RTJ, sheet & kammprofile gaskets. ASTM A193 B7 stud bolts & A194 2H nuts for all flange classes. NACE MR0175 & IBR approved grades. Sizes ½″ to 48″, Class 150 to 2500. PAN India delivery from Noida, UP.
🔵 Gaskets
Spiral wound · RTJ · Sheet · Kammprofile · Non-metallic
🔩 Fasteners
Stud bolts · Hex bolts · Heavy hex nuts · Washers · Threaded rods
Types of Flange Gaskets
Gaskets seal the mating faces of flanged joints — preventing leakage of oil, gas, steam, chemicals & other process fluids. Selecting the right gasket type for your flange class, service conditions and fluid is critical to joint integrity.
Spiral Wound Gasket (SWG)
Most Common — Process PipingThe industry standard for process piping — V-shaped metallic winding strips alternated with soft filler material. Three variants: 1) SWG with inner ring only, 2) SWG with outer ring (centering ring) only — for Raised Face flanges, 3) SWG with inner + outer rings — for all flange classes. Excellent resilience; self-energising under bolt load. Outer ring colour-coded by material for field identification.
Ring Type Joint (RTJ) Gasket
High-Pressure · Wellhead · Class 900–2500Solid metallic rings that seat in machined RTJ grooves on flanges — providing a metal-to-metal seal. Three ring profiles: R-ring (oval cross-section) for standard Class 900+ flanges; RX-ring (pressure-energised) — compatible with R-groove; BX-ring for API 6A wellhead equipment only. Material must be softer than flange material to deform and seal into grooves.
Full Face & Sheet Gaskets
Low–Medium Pressure · Non-MetallicDie-cut from sheet material — rubber (NBR, EPDM, Neoprene), compressed non-asbestos fibre (CNAF), PTFE (white & envelope), graphite sheet or laminated metal-clad. Full face (FF) extends across entire flange face including bolt holes — for cast iron & non-metallic flanges. Ring gasket (RG) fits between bolt holes on raised face flanges. Custom-cut sizes available to drawing.
Kammprofile Gasket
Heat Exchangers · High PerformanceA grooved solid metal core with soft sealing layers (graphite or PTFE) bonded to both faces. The concentric serrations (kammprofile = comb profile) create multiple sealing lines that lock in the soft layer under bolt load — achieving lower bolt forces than SWG while maintaining excellent blowout resistance. Preferred for heat exchanger channel covers, reactor flanges & critical high-pressure joints.
Jacketed & Metal-Jacketed Gaskets
Valve Bodies · Equipment NozzlesA soft filler core (graphite, ceramic or PTFE) enclosed in a thin metallic jacket (SS 304, SS 316, Inconel or soft iron). The jacket protects the filler and provides blowout resistance. Corrugated metal gaskets (CMG) use corrugated metal foil with soft facing — for pipe flanges, valve bodies & heat exchanger covers where low bolt loads are required.
Flange Isolation Gasket Kits
Cathodic Protection · Buried PipelinesComplete flange isolation kit: GRE/G10 dielectric gasket + insulating sleeves (for bolts) + insulating washers + steel washers. Prevents galvanic current flow between dissimilar metals in buried or underwater pipeline systems. Essential at pipeline inlet/outlet to cathodically protected sections. Available for ASME Class 150 to 1500, all NPS sizes.
Gasket Selection Matrix
Match your flange class, facing type and service conditions to the correct gasket — the most critical joint integrity decision in any piping project.
| Gasket Type | Flange Class | Facing Required | Temp. Range | Pressure Rating | High Temp | Sour Service | Cryogenic |
|---|---|---|---|---|---|---|---|
| SWG — Graphite Filler | Class 150–2500 | Raised Face (RF) | –200°C to +450°C | All pressures | ✓ | ✓ | ✓ |
| SWG — PTFE Filler | Class 150–600 | Raised Face (RF) | –200°C to +260°C | Class 150–600 | ✗ | ✓ | ✓ |
| RTJ — R-Ring (Oval) | Class 900–2500 | Ring Type Joint (RTJ) | –100°C to +650°C | Very High | ✓ | ✓ | ✗ |
| RTJ — RX Ring | Class 900–2500 | RTJ (R-compatible) | –100°C to +650°C | Very High | ✓ | ✓ | ✗ |
| Full Face Sheet (PTFE) | Class 150–300 | Full Face (FF) | –200°C to +260°C | Low–Medium | ✗ | ✓ | ✓ |
| Sheet — CNAF | Class 150–600 | FF / RF | –50°C to +350°C | Low–Medium | ✓ | ✓ | ✗ |
| Kammprofile — Graphite | Class 150–2500 | RF (machined) | –200°C to +550°C | All pressures | ✓ | ✓ | ✓ |
| Isolation Kit (GRE) | Class 150–1500 | RF | –50°C to +100°C | As per class | ✗ | ✗ | ✗ |
RTJ Ring Profiles & Materials
RTJ ring gaskets require precise material hardness selection — the ring must be softer than the flange groove material to form a proper seal.
R-Ring — Oval Cross-Section
Standard RTJ profile per ASME B16.20. Seats in a trapezoidal groove. Used for Class 900–2500 flanges in process piping. Sizes R-11 to R-104. Available in soft iron (BHN 90 max), SS 304/316 (BHN 160 max), Monel 400 & Inconel 625.
RX-Ring — Pressure-Energised
Interchangeable with R-groove but octagonal cross-section. System pressure acts on the ring to increase sealing force — self-energising design. Better than R-ring for cyclic pressure service. Same materials as R-ring. Sizes RX-20 to RX-210.
BX-Ring — API 6A Wellhead
Exclusively for API 6A wellhead & Christmas tree equipment. Octagonal cross-section seated in BX-specific grooves — provides positive pressure seal for wellhead pressures up to 20,000 psi. Sizes BX-150 to BX-303. Soft iron only per API 6A.
RTJ Material Hardness Rule
Ring material BHN must be lower than flange groove surface. Typical: Soft Iron (BHN 90) → Carbon Steel flanges. SS 304/316 (BHN 160) → Stainless flanges. Monel 400 (BHN 160) → High-alloy flanges. Never reuse an RTJ ring — always replace on reassembly.
SWG Component & Colour Code Guide
Understanding what you order when specifying a spiral wound gasket — every component affects sealing performance.
Winding Material (Inner Metallic Strip)
SS 304 — general service. SS 316 — chloride environments. Inconel 625 — high temp / aggressive. Hastelloy C276 — severe corrosion.
Filler Material (Soft Strip)
Graphite — high-temp, steam, oil & gas (to 450°C). PTFE — chemical service, acids, food-grade (to 260°C). Ceramic — extreme high-temp above 450°C.
Outer Centering Ring
Carbon steel (painted) or SS — locates gasket on RF flange, prevents over-compression. Colour coded: Yellow = CS, Green = SS 304, Bright Green = SS 316, Blue = SS 347.
Inner Ring
Optional inner ring prevents inward buckling of winding at high bolt loads and inner bore erosion. Required for Class 900+ and all ASME Class 600 NPS 24+. Same material as winding typically.
Standard Ordering Code
State: NPS × Class × Winding material / Filler material / Outer ring material. e.g. "6″ Class 600 · SS 316 / Graphite / CS ring".
Bolts, Studs & Nuts for Flanged Joints
High-strength certified fasteners for every flange class — from Class 150 carbon steel to Class 2500 sour service NACE-compliant stud bolt sets.
Stud Bolts
ASTM A193 B7 / B7M / B8 / B8M / L7Fully threaded studs with two heavy hex nuts — the standard fastener for ASME B16.5 flanged joints. B7 (chrome-moly, high-strength) for standard service. B7M (lower hardness) for NACE sour service. B8M (SS 316) for stainless flanges. L7 (low-temperature alloy) for cryogenic service to –100°C. Hot-dipped galvanized, Xylan & PTFE coated options available.
Heavy Hex Nuts
ASTM A194 2H / 2HM / 8M / 4Heavy hex nuts for use with ASME flange stud bolts — wider across-flats vs. standard hex for full thread engagement. 2H (carbon steel, quenched & tempered) — paired with B7 studs. 2HM for NACE service (lower hardness). 8M (SS 316) for stainless studs. Grade 4 (low-temp) for L7 studs. Always specified as matched set with stud grade.
Hex Bolts
ASTM A307 Gr.B / A449 / A325Machine hex bolts with one hex nut — used for Class 150 ASME flanges and non-critical equipment connections. A307 Gr.B for ASME Class 150 flanges. A449 for medium-strength general purpose. A325 for structural & equipment bolt-up. Hot-dipped galvanized (HDG) as standard for outdoor installations.
Washers & Threaded Rods
ASME B18.21.1 / ASTM F436 / A193 B7Washers (plain, spring, hardened) distribute bolt load on softer flange facing materials — specified for isolation gasket kits. Threaded rods (full-length studs) in A193 B7, B8M & L7 for custom stud bolt lengths in special flanges & equipment connections. Available in coated, uncoated & PTFE-lubed finishes.
Bolt Grade & Material Reference Tables
The most important reference for specifying correct stud bolt & nut combinations for every service condition — from standard process to NACE sour & cryogenic.
Stud Bolt Specification Guide — ASTM A193
| Grade | Material | Min. Yield | Nut Grade | Best For |
|---|---|---|---|---|
| B7 | Cr-Mo Alloy Steel (4140/4142) | 725 MPa | 2H | Standard process, Class 150–2500 |
| B7M | Cr-Mo (max 235 BHN) | 550 MPa | 2HM | NACE sour service, H₂S environments |
| B8 / B8M | SS 304 / SS 316 | 207 MPa | 8 / 8M | SS flanges, corrosive & high-temp |
| L7 | Cr-Mo Alloy (low-temp) | 725 MPa | 4 | Cryogenic service to –100°C |
| L7M | Cr-Mo (NACE + low-temp) | 550 MPa | 7M | Cryogenic & sour service combined |
| B6 | 410 Martensitic SS | 552 MPa | 6 | Elevated temp, mild corrosion |
Flange Class → Recommended Stud & Gasket
| ASME Class | Facing | Gasket Type | Stud Grade | Nut Grade |
|---|---|---|---|---|
| Class 150 | FF / RF | Full Face / CNAF Sheet | A307 Gr.B hex | A563 |
| Class 300 | RF | SWG (no inner ring) | A193 B7 | A194 2H |
| Class 600 | RF | SWG with inner ring | A193 B7 | A194 2H |
| Class 900 | RTJ | R-Ring / RX-Ring | A193 B7 | A194 2H |
| Class 1500 | RTJ | RX-Ring | A193 B7 (heavy) | A194 2H |
| Class 2500 | RTJ | RX-Ring / Kammprofile | A193 B7 (heavy) | A194 2H |
| NACE (any class) | RF / RTJ | SWG Graphite or RTJ | A193 B7M | A194 2HM |
A193 B7 Stud Bolt Torque Values
Indicative torque values for ASTM A193 B7 stud bolts with Molykote-lubricated threads (K = 0.15). Always verify against ASME PCC-1 calculations for your specific joint.
| Stud Dia. | TPI (UNC) | Stress Area (mm²) | Target Torque (Nm) | ASME Class |
|---|---|---|---|---|
| ½″ | 13 | 126 | 68 | 150–300 |
| ⅝″ | 11 | 198 | 135 | 150–600 |
| ¾″ | 10 | 285 | 230 | 150–900 |
| ⅞″ | 9 | 388 | 360 | 300–900 |
| 1″ | 8 | 506 | 510 | 300–1500 |
| 1⅛″ | 8 | 647 | 735 | 600–1500 |
| 1¼″ | 8 | 803 | 1020 | 900–2500 |
| 1½″ | 8 | 1160 | 1700 | 1500–2500 |
ASME PCC-1 Bolt Torqueing Procedure
Correct bolt tightening sequence is as critical as the torque value — wrong technique causes gasket distortion and joint leaks.
Preparation & Lubrication
Clean flange faces & inspect gasket seating. Apply Molykote G-Rapid Plus or Molyslip to stud threads & nut bearing face. Never dry-torque — friction coefficient doubles without lube.
Hand-Tighten All Bolts
Thread all studs and hand-tighten nuts finger-tight in cross-pattern (diametrically opposite pairs) to seat gasket evenly on flange face.
Pass 1 — 30% Target Torque
Apply 30% of target torque in cross-pattern. This begins seating the gasket without eccentric loading.
Pass 2 — 70% Target Torque
Apply 70% cross-pattern. Check flange gap is closing evenly — maximum 0.8mm difference across face at this stage.
Pass 3 — 100% Target Torque
Apply full target torque in cross-pattern. Then go around clockwise to verify all bolts are at target — SWG creep relaxation absorbs 5–15% of bolt load.
⚡ For Class 900+: Use hydraulic bolt tensioning for stud diameters ≥1″ to achieve uniform bolt load and eliminate cross-tightening scatter. ASME PCC-1 Appendix O methodology recommended.
Certifications & Standards
All Petropipe gaskets & fasteners are supplied with full test documentation — MTC, mechanical & chemical reports, and hardness certification for NACE service.
ASME B16.20 — Metallic Gaskets
Metallic & semi-metallic gaskets for pipe flanges — covers spiral wound gaskets (SWG), kammprofile, jacketed gaskets and ring type joint (RTJ) gaskets. Dimensional & material requirements for all standard pipe flange sizes and pressure classes.
ASME B16.21 — Non-Metallic Gaskets
Gaskets for pipe flanges — covers non-metallic, full-face and ring gaskets in sheet materials (rubber, PTFE, CNAF). Dimensional requirements for gasket OD, ID, thickness & bolt hole pattern to match ASME B16.5 flanges from Class 150 to 2500.
API 6A — Wellhead Gaskets
RTJ ring gaskets and wellhead sealing elements per API Specification 6A for wellhead Christmas tree equipment. BX-ring profile unique to API 6A, rated up to 20,000 psi (PR1 & PR2). Soft iron material per API 6A Annex H hardness requirements.
ASTM A193 — Bolting Materials
Standard specification for alloy-steel and stainless-steel bolting for high-temperature and high-pressure service. Covers all B-series grades (B7, B7M, B8, B8M, L7, L7M, B6). Mandatory for all ASME B16.5 Class 300+ flange bolt-ups.
ASTM A194 — Nuts
Standard specification for carbon and alloy steel nuts for high-pressure and high-temperature service. Covers 2H, 2HM, 4, 8, 8M grades. Each nut grade is specified with its matching stud grade per ASME B16.5 bolt-up tables.
NACE MR0175 / ISO 15156
Sour service material requirements for gaskets & fasteners in H₂S environments. Stud bolts: B7M max 235 BHN. Nuts: 2HM max 235 BHN. SWG inner ring & centering ring hardness requirements apply. Mandatory for ONGC sour gas fields & offshore platforms.
Why Choose Petropipe for Gaskets & Fasteners?
India's procurement engineers trust Petropipe because we supply the right gasket-bolt combination — fully documented, for every service condition.
Complete Flange Joint Packages
We supply gaskets + stud bolts + nuts as a complete, matched flange joint package — reducing procurement effort and eliminating compatibility errors between independently sourced components.
Full MTC & Hardness Certification
Every stud bolt and nut comes with ASTM A193/A194 MTC including chemical composition, mechanical properties (yield, tensile, elongation) and Brinell hardness — critical for NACE MR0175 compliance documentation.
Technical Selection Support
Our team recommends the correct gasket type, filler material, RTJ ring profile and stud bolt grade for your service conditions — temperature, pressure, fluid type, NACE requirements and flange facing — free of charge.
PAN India Express Delivery
Standard SWG gaskets and A193 B7 stud sets for common flange sizes dispatched within 24 hours. Custom SWG, RTJ rings and NACE-rated B7M sets on short lead times from our Noida warehouse.
Bulk & Turnaround Supply
Plant turnaround gasket & bolt kits — pre-kitted per flange size and class, tagged by line number — available for planned shutdown projects. Competitive pricing for high-volume orders from refineries, power plants and pipeline operators.
Get Gasket & Bolt Quote
Response within 2 business hours.
Gasket & Fastener Maintenance Best Practices
Proper gasket & fastener management prevents flange leaks, fugitive emissions and costly unplanned shutdowns in Indian oil & gas facilities.
Always Replace Gaskets
Never reuse a gasket after disassembly — compressed gaskets lose their sealing capability. This is especially critical for SWG and RTJ rings. Stock a set of spare gaskets matching every flange size in your plant for rapid turnaround. Use pre-kitted gasket sets tagged by line number for planned shutdowns.
Bolt Torque Verification
Check flange bolt torque at first heat cycle after startup — SWG graphite filler creep relaxes bolt load by 5–15%. Re-torque per ASME PCC-1 cross-pattern procedure. Mark verified bolts with paint marker. Hydraulic tensioning recommended for Class 900+ flanges to eliminate torque scatter (>±25%).
Fastener Inspection
Inspect stud bolts for corrosion, thread damage, stretch marks & coating condition at each turnaround. Measure stud elongation with ultrasonic bolt gauge for critical joints. Replace corroded or thread-damaged studs — never rethread and reuse. Apply fresh Molykote or anti-seize compound on reassembly.
Storage & Handling
Store gaskets in a cool, dry location away from sunlight, oils & solvents. Keep PTFE & rubber gaskets in sealed polythene bags — UV exposure degrades elastomers. Store RTJ rings in individual protective packaging to prevent groove damage. Tag stud bolt sets by class and size for rapid identification during turnarounds.
Complete Your Flanged Joint
Gaskets & fasteners seal and secure the joints between flanges, pipes and valves — source everything from Petropipe as a single package.
Flanges
ASME B16.5 weld neck, slip-on, blind & RTJ flanges. Class 150–2500. All materials.
Pipes
API 5L, ASTM A106 seamless & welded pipes in carbon, SS & alloy steel.
Industrial Valves
API 600/6D gate, ball, globe, check & butterfly valves. Class 150–2500.
Pipe Fittings
ASME B16.9 elbows, tees, reducers, caps & branch olets. All grades.
Ready to Source Gaskets & Fasteners?
Get competitive quotes for SWG gaskets, RTJ rings, A193 B7 stud bolts & complete flange joint packages — with full MTC documentation and PAN India delivery. Turnaround kits available.