# Instrument tube fitting

> Compression tube fittings in 316 stainless steel for ASTM A269 instrument tubing, without welding, and what a request needs: tube OD, thread type and style.

URL: https://jjprojectsok.com/products/electrical-instrumentation/tube-fitting  
Español: https://jjprojectsok.com/es/products/electrical-instrumentation/tube-fitting  
Updated: 2026-10-16

Compression fitting that joins small-diameter instrument tubing to equipment or other tubing without welding.

**In short:** Compression fitting that joins small-diameter instrument tubing to equipment or other tubing without welding. JJ Projects sources it to the specification the buyer names. Typical reference, tubing: ASTM A269 seamless and welded austenitic stainless tubing.

## Specification references

- Tubing: ASTM A269 seamless and welded austenitic stainless tubing
- Materials: 316 stainless steel typical
- Data to give: Tube OD in inch or metric, thread type and fitting style

> Typical references only. The governing specification is the one on your purchase order or datasheet.

## Typical uses

- Connecting instrument impulse lines to transmitters and manifolds
- Sampling systems and analyzer lines
- Chemical injection and small-bore hydraulic lines
- Panel and skid tubing where welding is not practical

## What to include in a request

A request with these details can be quoted without a round of questions. Send what you have and we will ask for the rest.

1. Tube outside diameter in inch or metric, for example 1/4 in or 6 mm, and the wall thickness
2. Fitting style: union, elbow, tee, male or female connector, bulkhead, cap or plug
3. End thread: NPT, BSP or ISO, and the size
4. Material, 316 stainless steel typical, or another alloy for the fluid
5. Pressure and temperature rating needed, checked against the manufacturer's data
6. Special cleaning, for example oxygen service, and quantity
7. Documents required, for example material test reports

[Request this item](https://jjprojectsok.com/request-a-quote?item=tube-fitting)

## Questions

### Are inch and metric tube fittings interchangeable?

No. A 1/4 in tube is 6.35 mm and a 6 mm tube is slightly smaller, so a fitting made for one will not seal reliably on the other. State the tube outside diameter and its unit.

### Can I mix fittings and ferrules from different manufacturers?

It is not recommended. Ferrule and body geometry differ between manufacturers, and mixed parts may not seal or hold pressure. Use the nut, ferrules and body of one manufacturer, and follow its tubing and installation instructions.

### What tubing does the fitting need?

Seamless or welded stainless tubing such as ASTM A269 in the stated outside diameter and wall, with a hardness within the fitting manufacturer's limit. A tube that is too hard or too thin may not seal.

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## Guides

- [How to write an RFQ for industrial materials](https://jjprojectsok.com/knowledge/how-to-write-an-rfq): What an RFQ for industrial materials must specify: item, size, schedule or class, grade, standard, quantity, MTRs, inspection, packing and Incoterm.
- [Valve types and standards: API and ASME B16.34](https://jjprojectsok.com/knowledge/valve-types-and-standards): Gate, globe, ball, check, butterfly and needle valves: what each does, which standards apply (API 600, 602, 6D, 608, 594, B16.34) and how to choose.

[All electrical and instrumentation](https://jjprojectsok.com/products/electrical-instrumentation)