How to Choose the Right Spiral Wound Gasket for Your Application?

What Are Spiral Wound Gaskets and Why Do They Matter

Spiral wound gaskets are semi-metallic sealing components constructed by winding a V-shaped metal strip and a soft filler material in alternating layers. The result is a gasket with exceptional resilience — it can compress under bolt load and spring back to maintain a seal under fluctuating pressure and temperature conditions.

They are the most widely used gasket type in critical industrial applications, including oil refineries, chemical processing plants, power generation facilities, and marine pipelines. Compared to flat sheet gaskets, spiral wound gaskets offer superior blowout resistance and a wider operational range — typically from -200°C to +1000°C and pressures exceeding 2500 PSI, depending on material selection.

Understanding their structure is the first step to choosing correctly:

• Winding metal: Provides structural integrity and pressure resistance (e.g., 304/316 stainless steel, Inconel, titanium)
• Filler material: Ensures sealing and chemical compatibility (e.g., flexible graphite, PTFE, ceramic fiber)
• Inner ring: Prevents inward buckling and reduces turbulence
• Outer ring (guide ring): Centers the gasket in the flange and acts as a compression stop

Key Selection Criteria: A Step-by-Step Decision Framework

Use this structured approach to narrow down your specification before placing an order.

Step 1 — Define Your Operating Conditions

Collect the following data from your process datasheet:

• Maximum operating temperature (°C or °F)
• Maximum operating pressure (PSI, bar, or MPa)
• Nature of the fluid (corrosive, oxidizing, cryogenic, steam, hydrocarbon)
• Cyclic loading or vibration present (yes/no)

Step 2 — Match Winding Metal to Temperature and Corrosion

The metal winding must resist both mechanical stress and chemical attack. The table below summarizes common choices:

Step 3 — Select the Right Filler Material

The filler determines sealing effectiveness and chemical compatibility. Flexible graphite is the most common choice, covering roughly 70% of industrial installations due to its excellent thermal stability and compressibility. PTFE filler is preferred when sealing aggressive acids or oxygen-rich environments.

• Flexible Graphite: -200°C to +550°C, resistant to most non-oxidizing media, ideal for steam and hydrocarbons
• PTFE: -200°C to +260°C, universal chemical resistance, suitable for food-grade and pharmaceutical applications
• Ceramic Fiber: Up to +1000°C, for extreme-temperature applications like furnace flue lines
• Mica: Up to +900°C, high-temperature insulation in power generation equipment

Step 4 — Identify the Correct Gasket Style

Spiral wound gaskets come in four standard configurations. Selecting the wrong style for your flange face type is a leading cause of premature seal failure.

• Style CG (with outer ring only): For raised face (RF) flanges in standard service
• Style CGI (with inner and outer rings): For RF flanges in high-pressure or cyclic service — the inner ring prevents inward buckling
• Style R (winding only): For tongue-and-groove or male-female flanges that fully confine the gasket
• Style RIR (with inner ring): For ring-type joint or special recessed flanges

Pressure and Temperature Capability: What the Data Shows

The chart below illustrates the operational envelope of the most common spiral wound gasket filler materials across temperature and pressure ranges. This is based on ASME B16.20 standard data and field performance records.

For pressure class, ASME B16.5 defines six pressure classes for flanges: Class 150, 300, 600, 900, 1500, and 2500. Your spiral wound gasket must be specified to match the flange class. A Class 600 flange operating at 300°C with 316 SS/graphite construction, for example, can handle up to approximately 68.3 bar (990 PSI).

Industry-Specific Application Guidance

Different industries impose different demands. Here is a concise reference for the most common sectors:

Oil and Gas / Petrochemical

Hydrogen sulfide (H2S) and high-pressure hydrocarbon streams are the dominant challenges. Recommended specification: 316L SS winding + flexible graphite filler + carbon steel outer ring, Style CGI. NACE MR0175 compliance is typically mandatory for sour service environments.

Chemical Processing

Chemical diversity means no single gasket fits all services. For acid service (pH below 3), use PTFE filler with Hastelloy C276 winding. For alkali service, graphite with Monel performs well. Always consult a chemical compatibility chart before finalizing.

Power Generation (Steam Systems)

Superheated steam at 540°C and 25 MPa is common in modern thermal power plants. Flexible graphite with 316 SS winding, Style CGI, is the industry benchmark. Ensure the inner ring is specified to prevent graphite extrusion into the flow path.

Shipbuilding and Marine

Saltwater and saline atmospheres demand superior chloride resistance. 316 SS or duplex stainless steel windings with graphite filler are standard. Inner and outer rings should also be 316 SS to prevent galvanic corrosion.

Standards and Certifications You Should Verify

Always confirm that the spiral wound gaskets you purchase comply with relevant international standards. Non-compliant gaskets may pass initial inspection but fail under thermal cycling or pressure surges.

• ASME B16.20: The primary standard for metallic gaskets for pipe flanges — defines dimensions, materials, and markings
• ASME B16.5: Governs flange pressure-temperature ratings and directly determines which gasket class is required
• API 6A / API 601: Required for wellhead and Christmas tree assemblies in oil and gas; includes additional hydrostatic and fire-resistance testing
• EN 1514-2: European equivalent standard for spiral wound gaskets for flanges to PN designations
• ISO 9001:2015: Quality management system certification ensuring consistent manufacturing process control

Always request mill test reports (MTRs) and manufacturer certificates of conformance. For regulated industries, third-party inspection and traceability documentation may be legally required.

Installation Best Practices That Affect Gasket Performance

Even a correctly specified spiral wound gasket will fail prematurely if installed improperly. The following practices are critical:

1. Clean flange faces thoroughly — remove all old gasket material, rust, and debris. A surface finish of 125–250 AARH (3.2–6.3 µm Ra) is recommended for spiral wound gaskets.
2. Center the gasket using the outer ring — do not rely on bolts for positioning. Misalignment of even 1–2 mm can result in uneven seating stress and localized leakage.
3. Lubricate bolt threads and nut faces — use a high-temperature anti-seize compound. This reduces friction coefficient and ensures accurate torque transfer.
4. Tighten bolts in a cross-bolt pattern — tighten in at least three passes: first to 30%, then 70%, then 100% of target torque. This ensures uniform gasket compression.
5. Never reuse spiral wound gaskets — once compressed, the filler material is permanently deformed. Reinstallation leads to insufficient seating stress and near-certain leakage.

About Ningbo Rilson Sealing Material Co., Ltd.

Ningbo Rilson Sealing Material Co., Ltd. was founded in 2007 and is a professional spiral wound gaskets manufacturer and supplier located in Ningbo, Zhejiang Province, China. The manufacturing facility spans across 20,000 square meters and is dedicated to ensuring the secure and dependable operation of fluid sealing systems, offering clients the appropriate sealing technology solutions.

Rilson operates numerous production lines for sealing products, specializing in the design and manufacture of sealing gaskets and other sealing materials for the petroleum, chemical, power, shipbuilding, and machinery manufacturing sectors. Primary products include spiral wound gaskets, ring joint gaskets, kammprofile gaskets, corrugated metal gaskets, insulation kit gaskets, and non-asbestos gaskets, among others.

Rilson's clientele hails from various parts of the globe. Through extensive industry experience, the company has earned the trust and recognition of customers worldwide and has obtained certifications from several prominent companies. Rilson has successfully achieved ISO 9001:2015 quality management system certification and the API 6A certificate, among others.

As a professional spiral wound gaskets factory, Rilson is dedicated to delivering value to customers, promoting health and happiness among workers, and producing positive social effects. Upholding the core principles of integrity, precision, innovation, and mutual success, Rilson is committed to becoming the preferred brand in industrial gaskets and a top-tier player in the fluid sealing industry.

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