ISO 6993-3:2006

Overview

ISO 6993-3:2006 specifies requirements for buried, high-impact poly(vinyl chloride) (PVC‑HI) fittings and saddles used to supply gaseous fuels at a maximum operating pressure of 1 bar (100 kPa). It covers full end‑load resistant components manufactured from PVC‑HI grades (PVC‑A, PVC‑CPE and PVC‑EPR) for buried pipelines with an operating temperature range of 0 °C to +30 °C, and applies to solvent‑cement and elastomeric‑seal joint types. The standard is intended for gases that do not contain components in concentrations that would damage the PVC‑HI materials.

Key topics and technical requirements

• Materials
  • Components must be made from high‑impact PVC (impact modifier ≥ 7% by mass).
  • Minimum long‑term strength (MRS) of the injection‑moulding material: ≥ 14 MPa (evaluated per ISO 9080).
  • Vicat softening temperature ≥ 74 °C (ISO 2507).
  • Resin K‑value > 57 (EN 922).
  • Elastomeric sealing elements to conform to EN 682:2002 (type G).
• Geometry and dimensions
  • Dimensional verification per ISO 3126; socket and spigot dimensions referenced to ISO 6993‑1 and ISO 4422‑3 where applicable.
  • Saddles have defined minimum wall thickness and cross‑sectional area by nominal pipe size (manufacturer declarations must meet these minimums).
• Physical and mechanical performance
  • Limits on contamination and surface defects (cracks, blisters, delaminations) after oven testing.
  • Resistance to external blows at 0 °C for fittings and saddles (test methods and acceptance criteria included); fittings must have a true impact rate (TIR) ≤ 5% under test conditions.
  • Leak‑tightness, tensile resistance of in‑line assemblies, and other performance tests are specified.
• Test methods and annexes
  • Normative annexes (A–F) detail test procedures for external‑blow resistance, tensile testing, leak tightness under internal/external pressure and mechanical loading, and more.

Practical applications

• Design, manufacture and quality assurance of buried PVC‑HI fittings and tapping saddles for low‑pressure gas distribution networks (up to 1 bar).
• Specification for procurement, type‑approval and factory testing of fittings and saddles used by gas utilities, pipeline contractors and component manufacturers.
• Guideline for performance testing in accredited labs to demonstrate compliance (impact resistance, leak tightness, long‑term material strength).

Who should use this standard

• Pipe and fitting manufacturers (moulding and compounding).
• Gas network designers, utilities and asset owners.
• Installation contractors and inspection/testing laboratories.
• Regulators and procurement teams specifying buried gas distribution components.

Related standards

• ISO 6993‑1, ISO 6993‑2, ISO 6993‑4 (other parts of the PVC‑HI gas piping series)
• ISO 9080, ISO 2507, ISO 3126, ISO 3127, ISO 4422‑3
• EN 682, EN 922

Keywords: ISO 6993‑3, PVC‑HI fittings and saddles, buried gas piping, 1 bar, solvent cement joints, elastomeric seals, MRS value, Vicat softening, impact resistance, tapping saddle.