Tube Diameter and Wall Thickness for Custom Coils

State OD and wall clearly

Use a format such as tube OD × wall thickness and include the material grade. Do not substitute nominal connection size for actual tube dimensions.

• Tube outside diameter
• Wall thickness
• Material grade
• Dimensional standard if controlled

Connect tube size to the geometry

Provide the required coil diameter, straight legs, pitch, number of turns and bend radii. The fabricator can then review whether the requested route is compatible with the defined tube.

• Coil or bend diameter
• Pitch and turn count
• Straight-leg length
• Overall envelope and tolerances

Add the operating basis

Pressure, temperature, medium and duty are part of the engineering review. Final wall and material selection should follow the approved project design and applicable requirements.

• Internal and external media
• Operating and design pressure
• Temperature range
• Required inspection or test

Use catalog examples correctly

The Uniinox custom coil catalog contains 304 stainless reference configurations at Ø9.52, Ø12 and Ø22 mm. These examples show documented geometries, not universal design recommendations.

• Ø9.52 × 0.7 reference
• Ø12 × 0.8 reference
• Ø22 × 1.0 references
• Approved drawing controls production

Record tube size as one controlled definition

State the actual tube outside diameter and wall thickness with units, then list the material grade and any dimensional standard or customer specification that controls tolerances. Record connection size and end preparation separately because a fitting or nominal connection is not automatically the tube dimension.

If an existing part is being replaced, note whether the dimensions were taken from a drawing, a nameplate, a measured sample or an assumption. This avoids treating an approximate field measurement as the approved manufacturing value.

Review tube size together with the formed geometry

A tube specification cannot be reviewed independently of coil diameter, pitch, bend radii, straight lengths, connection orientation and the available installation envelope. Mark controlled dimensions and identify where the fabricator may propose a geometry adjustment.

The listed catalog examples document shapes that have been supplied as references. They do not establish that the same tube and bend relationship is suitable for a different material, temper, service condition or tolerance set.

• Coil diameter or bend radius
• Pitch, turns and circuit arrangement
• Straight-leg and connection orientation
• Overall envelope and installation opening

Treat wall thickness as an engineering input, not a website recommendation

Wall review depends on the requested material, pressure, temperature, media, forming route, corrosion allowance where applicable and the governing project requirements. The website can collect those inputs but cannot assign a universal wall from outside diameter alone.

Material compatibility also remains service-specific. Nickel Institute guidance discusses how environment and contaminants can change stainless corrosion behavior and recommends professional advice for a particular application rather than a universal grade-selection table.

Define how dimensions and material will be accepted

List the dimensions that require inspection, the required material documentation and any project-specific pressure, leak or cleanliness checks. Separate requested inspection records from tests that have not yet been agreed.

Before production, place the tube definition, formed geometry, service basis and acceptance requirements on the same drawing or technical schedule. The approved revision should control both the first order and any repeat production.