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Pipe Sealant Selection Guide — Thread Sealant & Tape Decision Tool

Find the Right Pipe Thread Sealant for Your Application: PTFE Tape, Pipe Dope, Anaerobic, or O-Ring

Free pipe sealant selection tool for plumbers, pipefitters, maintenance technicians, and facility engineers. Enter the pipe material, fluid type, pressure rating, temperature range, and thread type to get a recommended sealant or sealing method. The tool covers PTFE tape, pipe dope (paste sealants), anaerobic thread sealants, PTFE paste, and O-ring mechanical seals.

Includes compatibility data for common pipe materials (steel, stainless, brass, copper, PVC, CPVC) and fluid services (water, natural gas, propane, compressed air, hydraulic oil, steam, refrigerants, and chemicals). Flags incompatible combinations that can cause joint failure, corrosion, or code violations.

Pro Tip: PTFE tape is not the universal answer. On natural gas joints, use yellow gas-rated tape or an approved pipe dope. On stainless steel, use nickel-based anti-seize or PTFE paste to prevent galling. On PVC and CPVC, never use petroleum-based dope, which attacks plastic. On oxygen service, never use any hydrocarbon-based sealant. The wrong sealant can be worse than no sealant.

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Reference flange bolt patterns for gasket-sealed connections

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Pipe Thread Sealant Guide
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How It Works

  1. Select Pipe Material

    Choose the pipe material: carbon steel, stainless steel, brass, copper, PVC, CPVC, cast iron, or galvanized. The material determines sealant compatibility. Plastic pipes have restrictions on petroleum-based products. Stainless requires anti-galling compounds.

  2. Select Fluid Service

    Choose what the pipe carries: potable water, non-potable water, natural gas, propane, compressed air, hydraulic oil, steam, refrigerant, or chemical. Some services have code-mandated sealant requirements (gas requires approved sealants, potable water requires NSF 61 approved products).

  3. Enter Pressure and Temperature

    Specify the maximum operating pressure in PSI and the temperature range. High-pressure and high-temperature services may eliminate PTFE tape as an option and require anaerobic or PTFE paste sealants rated for the conditions.

  4. Select Thread Type

    Choose the thread standard: NPT (tapered), NPS (straight/parallel), BSP tapered, or BSP parallel. Tapered threads (NPT) create a mechanical seal with thread engagement. Straight threads (NPS, BSP parallel) require an O-ring or gasket for sealing.

  5. Review Sealant Recommendation

    The tool recommends a sealant type, application method, and any code requirements. Warnings appear for incompatible combinations. The recommendation includes brand-agnostic product descriptions and application tips.

Built For

  • Plumbers selecting thread sealant for potable water, gas, and drain systems per local code
  • Industrial pipefitters choosing sealants for steam, compressed air, and hydraulic connections
  • Maintenance technicians identifying the correct sealant for emergency pipe repairs in chemical plants
  • HVAC technicians selecting sealants for refrigerant piping and natural gas connections
  • Facility engineers establishing approved sealant lists for maintenance storerooms
  • Fire protection installers selecting sealants for sprinkler system pipe joints
  • Apprentice plumbers learning which sealants are code-compliant for different services
  • Home DIYers identifying the right sealant for gas, water, and compressed air connections

Features & Capabilities

Material Compatibility Matrix

Cross-references pipe material with sealant type to flag incompatible combinations. PVC plus petroleum dope, stainless plus steel-based anti-seize, and oxygen service plus hydrocarbon sealant are all flagged with warnings.

Code Compliance Flags

Identifies code requirements including NSF 61 approval for potable water, IFGC-approved products for natural gas, NFPA 13 requirements for fire sprinkler systems, and ASME B31.3 requirements for process piping.

Temperature and Pressure Ratings

Shows the service temperature and pressure limits for each recommended sealant type. PTFE tape: -450 to 500 deg F. Standard pipe dope: -50 to 300 deg F. Anaerobic: -65 to 400 deg F. High-temperature paste: to 750 deg F.

Application Instructions

Provides application guidance for each sealant type: number of tape wraps, clockwise direction, thread engagement, cure time for anaerobic sealants, and surface preparation requirements.

Thread Type Guidance

Explains the sealing mechanism for each thread type. NPT threads seal on the thread taper. NPS and BSP parallel threads do not seal on the threads and require an O-ring, gasket, or compression fitting.

Incompatibility Warnings

Prominent warnings for dangerous combinations: never use hydrocarbon-based sealant on oxygen service, never use petroleum-based products on PVC/CPVC, never use standard tape on medical gas, and never use non-approved sealant on potable water.

PDF Export

Export your sealant recommendation as a branded PDF for maintenance work orders, procurement specifications, or training documentation.

Frequently Asked Questions

Yes, but only yellow gas-rated PTFE tape that is thicker and denser than standard white tape. Standard white PTFE tape is not code-approved for gas in most jurisdictions. Gas-rated tape is typically 0.004 inches thick versus 0.003 inches for standard tape, and is marked for gas service. Many inspectors also accept approved pipe dope on gas joints.
Use PTFE tape or a PTFE-based paste sealant. Never use petroleum-based pipe dope on plastic pipe, as the petroleum solvents can attack the plastic, weaken it, and cause joint failure. For CPVC specifically, use only products approved for CPVC, as some chemicals cause environmental stress cracking.
No. Compression fittings seal on the ferrule (olive) that compresses against the tube. Adding tape or dope to a compression fitting can prevent the ferrule from seating properly and may cause leaks. The same applies to flare fittings, which seal metal-to-metal at the flare.
PTFE tape fills thread gaps with a thin layer of PTFE that acts as both lubricant and sealant. Pipe dope (paste sealant) fills thread voids with a thicker compound that sets up or remains pliable depending on the formula. Pipe dope is generally better for large-diameter threads and vibration-prone joints. PTFE tape is simpler and cleaner for small-diameter fittings.
Yes, many professionals use both on critical joints: apply pipe dope to the male threads first, then wrap with PTFE tape. This provides redundant sealing. However, some specifications prohibit double-sealing, so check your project requirements. For most residential and commercial plumbing, one or the other is sufficient.
Any sealant used on potable water supply piping must be NSF 61 certified, which verifies that the product does not leach contaminants into drinking water. Most PTFE tape is NSF 61 listed. Many pipe dope products are also NSF 61 certified, but check the label. Non-certified products are a code violation on potable water systems.
Disclaimer: Sealant recommendations are general guidance based on material compatibility and common industry practice. Always verify sealant selection against the applicable plumbing code, mechanical code, fire code, or process piping standard for your jurisdiction. Some applications require specific listed or approved products. When in doubt, consult the pipe and sealant manufacturer documentation.

Learn More

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Pipe Thread Sealant Selection Guide: PTFE Tape, Pipe Dope, Anaerobic & O-Ring

How to choose the right pipe thread sealant for any material, fluid, and pressure. Covers PTFE tape types, pipe dope, anaerobic sealants, compatibility rules, and code requirements.

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