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Guide for gas transmissions and distribution piping system 1986 add 3 — ASME Guide for Gas Transmission and Distribution Piping Systems, 1986, Addenda No. 3
📘 Guide for gas transmissions and distribution piping system 1986 add 3 is Addenda No. 3 to the 1986 Edition of the ASME Guide for Gas Transmission and Distribution Piping Systems, a 35-page document issued in November 1987. The Addenda continues the loose-leaf maintenance mechanism of the Guide: it updates the 1986 text with replacement pages, marks the changed areas with bullets, and advises users to retain the superseded pages to preserve the chronological evolution of the federal safety standards and the Guide. The change summary covers an errata to the repair-or-removal rule for weld defects (192.245), revisions and additions of guide material on plastic pipe jointing (192.281/192.283), and updated guide material for operations and maintenance provisions (192.733/192.751).
💡 An addenda is the “upgrade package” of the loose-leaf system: it does not change the Guide’s philosophy but translates the latest federal amendments (such as the 49 CFR Part 192 revisions) into the Committee’s newest how-to advice. Replace pages promptly and keep the old ones.
1. Overview of the Addenda Contents 📌
The Addenda’s “Summary of Changes” lists the pages to replace or insert, together with the corresponding section and the type of change — errata to a federal standard or revision/addition of guide material. The main changes are summarized below:
| Section | Type of Change | Subject |
|---|---|---|
| 192.245 | Errata to federal standard | Repair or removal of weld defects |
| 192.281 | Revision of guide material | Plastic pipe jointing: solvent cement, heat fusion, adhesive, mechanical |
| 192.283 | Addition of guide material | Additional requirements for plastic pipe components and valves |
| 192.733 | Revision of guide material | Operations and maintenance: leak surveys and patrols |
| 192.751 | Revision of guide material | Operations and maintenance: valve maintenance and operation |
⚠️ The amendments to 49 CFR Part 192 that follow this Addenda are included for information only; they are not part of the Gas Guide or the Addenda. Always distinguish between “federal standard text” and “ASME guide material” when citing provisions.
2. 192.245: Repair or Removal of Defects (Errata Highlights) 🔧
Section 192.245, “Repair or removal of defects,” prescribes how unacceptable welds are handled; this Addenda makes an errata to the federal standard. Its core rules include:
- Each weld unacceptable under 192.241(c) must be removed or repaired;
- Except for welds on an offshore pipeline being installed from a pipeline vessel, a weld must be removed if it contains a crack more than 8 percent of the weld length;
- Each weld that is repaired must have the defect removed down to sound metal, and the segment must be preheated if conditions exist that would adversely affect the quality of the repair;
- After repair, the repaired segment must be inspected to ensure acceptability;
- Repair of a crack, or of any defect in a previously repaired area, must follow a written weld repair procedure qualified under 192.225, and the procedure must achieve the minimum mechanical properties specified for the original welding procedure upon completion of the final repair.
🚨 The “crack over 8 percent of weld length requires entire weld removal” rule is not overkill: cracks are precursors of brittle failure. Never simply patch an unacceptable crack and skip re-examination — follow removal or qualified repair with post-repair inspection.
3. 192.281: Plastic Pipe Jointing Guide Material (Main Content) 🔥
This Addenda substantially revises the guide material under 192.281, “Plastic pipe,” giving systematic advice on jointing. The guide material stresses at the outset that plastic pipe joints must be made by personnel qualified by training or experience, using qualified written procedures, proper materials, and equipment in good condition. Solvent-cement or heat-fusion joints should be made only between components of the same basic thermoplastic materials; heat fusion or mechanical joints should be used when joining polyethylene components.
💡 Plastic pipe calls for “less flame, more precision”: unlike steel, plastic joint quality depends almost entirely on surface preparation, heating temperature, and timing. Rain, cold, and wind can significantly affect fusion quality, so adjust the procedure’s heating time accordingly.
The specific requirements for each joint type are summarized as follows:
- Solvent cement: mating surfaces must be clean, dry, and free of detrimental material; the cement must meet ASTM D 2513; heating to accelerate setting is prohibited; ends must be square-cut and free of burrs; for diameters greater than 2 inches, additional measures may be needed to bottom the pipe; the joint must not be pressure-tested until it has developed a high percentage of its ultimate strength.
- Heat fusion: a butt fusion joint must use a device that holds the heating element square to the ends, compresses the heated ends together, and holds alignment while the plastic hardens; a socket fusion joint must heat the mating surfaces uniformly and simultaneously to essentially the same temperature; heat may not be applied with a torch or other open flame.
- Adhesive: the adhesive must meet ASTM D 2517 and be compatible with the materials; apply liberally to both surfaces and hold the joint in alignment until the adhesive sets.
- Mechanical (compression) joints: the elastomeric gasket must be compatible with the plastic; a rigid internal tubular stiffener (not a split stiffener) must be used; joints must be designed to sustain longitudinal pull-out forces from contraction and maximum external loading, using practices such as snaking in the ditch, anchoring, strapping, expansion-contraction devices, and placement in compression.
4. Engineering Practice Essentials 🛠️
- 🔍 Distinguish “shall” from “should”: federal standard text (shall) and guide material (should) differ in mandatory weight; cite them separately in engineering documents and do not turn recommendations into requirements.
- 📊 Joint quality control: training, procedures, and weather are the keys to plastic pipe joint quality; keep joint records (time, temperature, operator) for traceability and re-inspection.
- 📋 Document repair procedures: weld repairs must follow written procedures qualified under 192.225; keep repair records, examination results, and personnel qualifications on file for quality audits.
- 📐 Timing of pressure tests: solvent-cement and adhesive joints must not be tested until they develop a high percentage of ultimate strength; test pressure and hold time follow the federal standard and the procedures.
5. Frequently Asked Questions ❓
❓ Q: How do the Addenda relate to the 1986 Guide text?
A: The Addenda update the text via replacement pages: insert the revised pages into the binder while retaining the old ones, giving you a complete record of “current requirements plus history.” The philosophy is unchanged; the latest pages govern.
A: The Addenda update the text via replacement pages: insert the revised pages into the binder while retaining the old ones, giving you a complete record of “current requirements plus history.” The philosophy is unchanged; the latest pages govern.
❓ Q: Can plastic pipe be joined with threaded joints?
A: No — 192.281 explicitly prohibits threaded joints and miter joints on plastic pipe. Permitted jointing methods are solvent cement, heat fusion, adhesive, and mechanical (compression) joints.
A: No — 192.281 explicitly prohibits threaded joints and miter joints on plastic pipe. Permitted jointing methods are solvent cement, heat fusion, adhesive, and mechanical (compression) joints.
❓ Q: Why must a weld with a crack over 8 percent of its length be entirely removed?
A: Cracks are planar flaws with severe stress concentration and high propagation risk; local excavation may fail to eliminate them completely and the repair itself can become a new weak point. The Code therefore requires removal of the whole weld in that case, allowing repair only for other defects under controlled conditions.
A: Cracks are planar flaws with severe stress concentration and high propagation risk; local excavation may fail to eliminate them completely and the repair itself can become a new weak point. The Code therefore requires removal of the whole weld in that case, allowing repair only for other defects under controlled conditions.
❓ Q: What should be checked before a pneumatic test?
A: Follow the federal standard and guide material on pressurization sequence, safety exclusion zones, and leak checks. Perform a low-pressure leak check first, then pressurize in slow stages; keep personnel away from the test section and verify temperature compensation and flaw evaluation.
A: Follow the federal standard and guide material on pressurization sequence, safety exclusion zones, and leak checks. Perform a low-pressure leak check first, then pressurize in slow stages; keep personnel away from the test section and verify temperature compensation and flaw evaluation.
