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Technical Notes

Composite Leak-Sealing — Details Decide

Bond sealant rod, fiber cloth and epoxy onto the defect to form a composite stronger than steel that shares load with the host. Hydrogen leaks and thermal cycling test every detail.

Published: 2020-06-02

Composite Leak-Sealing — Details Decide

Composite leak-sealing wraps a sealant rod, fiber cloth and epoxy resin around defective pipe, vessel or component, forming a composite system stronger than steel. The result is effectively a second pipe outside the host: pressure capacity rises and stress is shared with the host, keeping the defect below its safety limit.

Four-Step Workflow

  1. De-rust — strip rust, paint and loose contamination
  2. Plug the leak — apply sealant rod and matched consumables. For φ≤30 mm holes, glue a 0.2 mm stainless or aluminium foil with sealant. For larger holes, pass a T-bolt through, apply sealant around the hole, add a pierced 0.2 mm stainless plate and a 2–3 mm steel plate, tighten — extend stainless 50 mm beyond steel if it still leaks.
  3. Defect repair — fill corrosion pits and weld defects with repair compound, level the surface
  4. Reinforcement — wrap carbon-fiber, aramid or S-glass cloth with resin, cure

Why Details Decide

Hydrogen leaks illustrate the point: hydrogen molecules are small, rigid cure adhesives crack under vibration; fast-cure steel putty hardens too much and develops invisible micro-cracks as cooler temperatures cycle — and hydrogen permeates straight through. Elastic adhesives lack pressure-holding strength; high-strength rigid adhesives lack ductility. Blending two adhesives — chosen for line pressure and service temperature — often delivers the satisfactory result.

The process is broadly similar; materials vary; smart blending is fast and effective.