Weld Bung
1/4″ NPT MILD STEEL NPT WELD BUNG
NPT weld bungs from 1/8 NPT to 2″ NPT. Weld to any tube, tank, or manifold for sensor ports, drains, and fluid connections.
SKU: NPTWB-14-MS
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Technical Specifications
| Thread Standard | ASME B1.20.1 NPT (tapered) |
|---|---|
| Material | 304 Stainless or Mild Steel |
| Sizes | 1/8″ NPT – 1″ NPT |
| Weld Base | Hex flat or round flange |
| Seal | Teflon tape or thread sealant required |
| Applications | Sensor ports, drain plugs, coolant connections |
Frequently Asked Questions
Do NPT weld bungs need a sealant?
Yes. NPT is a tapered thread that relies on interference — it does not self-seal without sealant. Use PTFE (Teflon) tape or a thread sealant paste like Loctite 567 on all NPT connections. Never use thread sealant on the first thread — start from the second thread to prevent contamination of the line.
1/8 NPT vs 1/4 NPT for sensor ports?
Most oil pressure, fuel pressure, and coolant temp sensors use 1/8″ NPT threads. Air/boost pressure sensors are commonly 1/8″ NPT. The 1/4″ NPT size is standard for larger sensors, -4AN to NPT adapters, and inline bleeder fittings.
Can I weld NPT bungs to aluminum?
Yes. Use a mild-steel bung on steel fabrications and a 304 stainless bung on aluminum using a TIG welder with 4043 filler. An aluminum NPT bung is also available on request. Do not attempt to MIG-weld stainless bungs to aluminum.