Flange Isolation Gasket Kits (also known as Flange Insulation Sets) are critical safety and corrosion-prevention components used in petrochemical pipelines, oil and gas gathering systems, and offshore platforms. By stopping stray electrical currents and halting galvanic corrosion between dissimilar metal flanges, these specialized G10/G11 epoxy glass kits ensure effective Cathodic Protection (CP) and prevent catastrophic flange leaks under high pressure.
This technical guide from RDS Composite breaks down the full structural cross-section of flange isolation kits, specifies pressure, medium, and thermal limits, compares G10 vs. G11 retainer materials, and lists essential drawing parameters required for accurate custom RFQs.
1. System Architecture & Component Cross-Section
A complete G10/G11 Flange Isolation Gasket Kit is an engineered assembly comprising four primary insulating elements designed to completely seal the process fluid while electrically decoupling the flange faces and studs:
- 1. Main Isolating Retainer Gasket: A high-strength G10 or G11 glass-epoxy composite core retainer incorporating a spring-energized PTFE or Viton seal ring embedded in precision machining grooves.
- 2. Full-Length Isolating Sleeves: High-dielectric G10 or Mylar/Nylon cylindrical sleeves fitted over each flange bolt/stud to prevent metal-to-metal contact with the bolt holes.
- 3. Isolating Washers: High-compressive G10 or G11 glass-epoxy washers (1/8" / 3.2mm thick) placed under each nut to isolate axial bolt preload.
- 4. Steel Backup Washers: Zinc-plated carbon steel or Stainless Steel (SS316) washers placed over the isolating washers to evenly distribute heavy torque loads during bolt tensioning.
2. Operating Conditions: Pressure, Media & Temperature Ratings
A. Pressure Class Capacity
RDS G10/G11 isolation gaskets are engineered for high-pressure sealing across standard ASME/API pressure ranges:
- ASME B16.5 / B16.47 Flanges: Class 150, 300, 600, 900, 1500, and 2500.
- API 6A Wellhead Flanges: 2,000 psi to 10,000 psi rating (Type F and Type E configurations).
B. Chemical & Media Resistance
The G10/G11 epoxy matrix combined with specialized sealing element materials provides full chemical compatibility with harsh hydrocarbon process streams:
- Sour Service (H2S & CO2): Compliant with NACE MR0175 / ISO 15156 for sour crude oil and natural gas applications.
- Seal Ring Selection: Spring-Energized PTFE for cryogenic/sour gas; Viton/FKM for refined petroleum products; Nitrile (NBR) for standard water/glycol streams.
3. Material Selection Matrix: G10 vs. G11 Glass-Epoxy Retainers
Choosing between G10 (NEMA G10 / EPGC201) and G11 (NEMA G11 / EPGC203) matrix retainers depends primarily on operating thermal exposure and bolt-torque stress retention requirements:
| Engineering Parameter | G10 Epoxy Glass Matrix | G11 High-Temp Epoxy Matrix |
|---|---|---|
| Continuous Temp Rating | -40°C to +130°C (Class B) | -50°C to +180°C (Class H) |
| Glass Transition Temp (Tg) | ≈ 130°C – 140°C | ≥ 175°C – 180°C |
| High-Temp Compressive Strength | Softens at > 130°C under high torque | Retains ≥ 50% compressive modulus at 150°C |
| Primary Application Focus | Standard onshore oil/gas pipelines, water treatment, ambient refined product lines. | High-temperature steam lines, offshore topside facilities, thermal recovery wells. |
4. Critical Parameters Required for Custom RFQs & Drawings
To ensure flawless flange fitment and zero field leakage, please provide the following technical parameters when requesting a quote or submitting CAD drawings to RDS:
- Flange Standard & Nominal Pipe Size (NPS): e.g., 6" ANSI B16.5, 12" ASME B16.47 Series A, or API 6A 3-1/8".
- Pressure Class Rating: e.g., Class 150, Class 600, or 5000 psi.
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Flange Facing Type:
- Type E (Full Face): Gasket covers the entire flange face with cutouts for stud holes.
- Type F (Raised Face / Inside Bolt Circle): Fits entirely inside the stud bolt circle.
- Type D (Ring Type Joint - RTJ): Precision machined to fit metal RTJ oval/octagonal grooves.
- Sleeve Configuration: Single washer set (one sleeve + one G10 washer + one steel washer per bolt) or Double washer set (two washers per bolt for dual-side isolation).
- Operating Media & Working Temperature Range: Defines the elastomeric seal element (PTFE, Viton, or Nitrile) and retainer grade (G10 vs. G11).
Request Custom G10/G11 Flange Isolation Kit Quote
Need ASME B16.5 or custom API flange insulating sets for pipeline corrosion prevention? Submit your pipeline specifications or flange drawings to the engineering team at RDS Composite.
Submit Pipeline Drawing / Request Custom Quote