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SAE J2043: Nonmetallic Fuel System Tubing – Key Requirements and Design Insights
SAE J2043 specifies minimum requirements for nonmetallic tubing used in gasoline or diesel fuel systems. Although cancelled, this standard provides foundational design and testing criteria still referenced in many applications. Below we cover scope, material, construction, performance tests, and practical design insights.
1. Scope and Key Parameters
The standard applies to single-wall extruded tubing for use in gasoline or diesel fuel systems operating within –40 °C to 115 °C and a maximum working gage pressure of 690 kPa. It does not cover tubing for portions of the system operating outside these limits.
2. Material, Construction, and Labeling
Tubing must be made from virgin nylon 11 or 12 (polyamide) containing heat and light stabilizers. Plasticizers, colorants, and impact modifiers may be added, but no regrind is permitted. The material must meet ASTM D4000/D4066 requirements.
Color and identification: The tubing shall be black. A contrasting legend must appear every 380 mm or less along the entire length, in legible block capital letters. The minimum required information, in order, is: “Fuel” followed by “SAE J2043‑NNNN” (where NNNN is the nominal OD from Table 1).
| Nominal OD (mm) | Minimum ID (mm) | Wall Thickness (mm) | Bend Diameter (mm) |
|---|---|---|---|
| 6.35 | 3.89–4.14 | 0.98–1.14 | 76.2 |
| 7.93 | 6.20–6.50 | 0.90–1.15 | 101.6 |
| 9.53 | 7.90–8.20 | 0.90–1.15 | 152.4 |
3. Performance Testing and Quality Assurance
All performance tests must demonstrate ±3 sigma capability. Tubing shall be tested after a minimum of 24 h after manufacturing. Unless otherwise specified, test temperatures may vary ±2 °C and times are minimums.
Room Temperature Burst Test: Stabilize tubing ½ to 3 h at 23 °C, then increase pressure at a constant rate to reach 3500 kPa within 3 to 15 s. Continue at that rate until burst. The lower 3 sigma burst pressure must be ≥3500 kPa.
Cold Temperature Flexibility Test: Condition tubing 24 h at 110 °C, then within 30 min expose to –40 °C for 4 h (tubing and mandrel may be supported by a nonmetallic surface). Immediately bend 180° over a mandrel of diameter 12 times the nominal OD (bending motion completed in 4 to 8 s). No fracture allowed. After returning to 23 °C, the tubing must pass the Room Temperature Burst Test.
Zinc Chloride Resistance: Form a coil at the minimum bend diameter from Table 1, secure with copper wire or nylon 11/12 ties, and immerse in a 50% (by weight) aqueous zinc chloride solution for 200 h at 23 °C. No cracking on the outside diameter. Then subject to the Room Temperature Burst Test.
Burst Test – Kinked Tubing: (test method detailed in the standard).
🛠️ Engineering Design Insight
- Use only virgin nylon 11 or 12 with heat and light stabilizers; never use regrind.
- Ensure end fittings comply with SAE J2044 and are assembled without mechanical damage to the tubing.
- Route tubing to prevent chafing, abrasion, kinking, and other mechanical damage. Protect from road hazards by location or shielding.
- If temperatures exceed –40 °C to 115 °C, add insulation.
- Allow at least 24 h after manufacturing before any performance testing.
- All tests must demonstrate ±3 sigma statistical capability.
⚠️ Common Mistakes to Avoid
- Using regrind material (not permitted).
- Improper labeling: tubing not black, legend not contrasting, spacing >380 mm, missing “Fuel” and “SAE J2043‑NNNN”.
- Exceeding temperature limits (–40 °C to 115 °C) or working pressure (690 kPa) without additional protection.
- Failing to protect tubing from road hazards or chafing.
- Not verifying end fitting assemblies to SAE J2044.
- Performing tests without proper conditioning (e.g., burst test at wrong rate, not stabilizing temperature).
- Ignoring the ±3 sigma capability requirement.
Frequently Asked Questions
What materials are permitted for SAE J2043 tubing?
Only virgin nylon 11 or 12 (polyamide) with heat and light stabilizers. No regrind, plasticizers, colorants, or impact modifiers may be added as needed, but the base material must meet ASTM D4000/D4066.
What is the required burst pressure?
The lower 3 sigma burst pressure at room temperature must be at least 3500 kPa. The test must be conducted by increasing pressure at a constant rate to reach 3500 kPa within 3 to 15 s and continuing until burst.
How is cold flexibility tested?
Tubing is conditioned 24 h at 110 °C, then within 30 min exposed to –40 °C for 4 h. Immediately after, it is bent 180° over a mandrel having a diameter equal to 12 times the nominal OD (bending over 4 to 8 s). No fracture is allowed. The sample must then pass the room temperature burst test after returning to 23 °C.
What are the labeling requirements?
Tubing must be black with a contrasting legend repeated every 380 mm or less. The legend must include “Fuel” and “SAE J2043‑NNNN” (where NNNN is the nominal OD). Additional information may be added if needed.
Note: SAE J2043 was cancelled in 1996 but its technical requirements are still used as a reference for nonmetallic fuel system tubing design and validation.
