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D3681-23 – Standard Test Method Technical Guide
📐 Scope and Terminology
ASTM D3681-23 is issued under the fixed designation D3681, with the number indicating the year of adoption or revision. This test method covers the determination of chemical-resistant properties of fiberglass pipe in a deflected condition for diameters 4 in. (102 mm) and larger. Both glass-fiber-reinforced thermosetting resin pipe (RTRP) and glass-fiber-reinforced polymer mortar pipe (RPMP) are included. Inch-pound units are regarded as the standard.
Key terminology includes end point (passage of fluid through the pipe wall, often catastrophic fracture parallel to axis with cleanly broken fibers), fiberglass pipe (composite with glass fiber in cured thermosetting resin), RPMP (fiberglass pipe with aggregate), RTRP (without aggregate), and strain-corrosion (failure from strain and corrosive environment). Definitions per D883 and D1600.
Note 1: For this standard, polymer does not include natural polymers. Note 2: No known ISO equivalent.
⚙️ Test Procedure and Strain Conditions
The test method exposes a minimum of 18 pipe specimens to a corrosive solution while held in a deflected condition at differing induced initial ring flexural strain levels. Test temperatures are obtained via controlled air environment. Dimensions are measured per Practice D3567. The time to failure is measured for each strain level to evaluate chemical resistance.
| 🟦 Parameter | 📏 Value |
|---|---|
| Minimum Specimens | 18 |
| Pipe Diameter | ≥ 4 in. (102 mm) |
| Pipe Types | RTRP, RPMP |
| Strain Levels | Variable induced ring flexural strains |
| Environment | Controlled air temperature |
Precautionary statements are given in Section 9.5. Ensure proper safety measures.
📊 Key Measured Properties and Failure Criteria
The primary measured property is time to failure. Failure is defined by the end point: fluid passage through the pipe wall. This can be catastrophic, with a sudden fracture in the area of greatest strain, parallel to the axis, and with fiber reinforcement cleanly broken at the fracture edge. Surface etching or pitting may or may not be present.
Strain-corrosion is the failure mode of interest, resulting from exposure of the inner surface to a corrosive environment while in a strained condition.
| 🎯 Failure Criterion | 📐 Description |
|---|---|
| End Point | Fluid penetration through wall |
| Catastrophic Fracture | Sudden axial fracture, clean fiber break |
| Strain-Corrosion | Failure from stress and corrosion |
❓ Frequently Asked Questions
🔍 What is the purpose of ASTM D3681-23?
To determine chemical resistance of fiberglass pipe under deflection, simulating service conditions.
💡 How is failure defined in D3681?
Failure is defined by the end point: passage of test fluid through the pipe wall.
⚡ What pipe diameters are applicable?
Pipe diameters 4 in. (102 mm) and larger.
📌 What is strain-corrosion?
Failure of pipe wall due to corrosive exposure while in a strained condition.