Spark Exhaust Stainless Steel Tube Ø 28 × 1.5 mm 500 mm Universal G9010

Half a metre of straight AISI 304 at twenty-eight millimetres, and the only small-bore size in Spark's range with a wall a full millimetre and a half thick.

Key Features

• Straight exhaust tube, AISI 304 stainless steel.
• Ø 28 mm outside, 1.5 mm wall thickness.
• 500 mm long.
• The smallest diameter Spark stocks.
• Fabrication stock — cut, welded and fitted by the builder.
• Spark part number G9010, made in Mantova, Italy.

Why the Wall Is Thicker Here

Every tube Spark stocks between thirty-two and sixty millimetres has a one millimetre wall. This one, and the seventy-six at the other end of the range, have thicker ones.

The reason is stiffness. A tube resists bending in proportion to its diameter cubed, so a small tube is dramatically floppier than a large one at the same wall. At twenty-eight millimetres, one millimetre of stainless would kink under a bender and dent under a boot; a millimetre and a half does not.

What It Is For

Small-bore work. Balance pipes between headers, link sections on a 125 or a small single, breather and drain runs, and the short connecting pieces that a one-off system needs and no catalogue sells.

At this diameter it is rarely the main gas path on anything above 250 cc. It is the plumbing around the plumbing.

Cutting and Welding Stainless

Cut it with an abrasive wheel or a cold saw, not with a chop saw meant for mild steel — carbon contamination on the cut face is the most common cause of a stainless weld that rusts a year later.

TIG with a stainless filler and back-purge the inside. Without purge gas the root of the weld oxidises, goes granular and cracks under heat cycling. That is not a cosmetic issue on an exhaust.

AISI 304

The standard austenitic stainless: roughly eighteen per cent chromium, eight per cent nickel. It is the material almost every quality exhaust is built from, because it takes exhaust temperature without scaling and takes road salt without pitting.

It does work-harden as it is formed, which matters if you plan to bend it: bend once, deliberately, rather than adjusting a bend repeatedly.

Not Plumbing Tube

Decorative and sanitary stainless of the same nominal size is not the same product. Ornamental tube is made to a looser wall tolerance and is often welded from strip with an internal bead that has never been removed — a ridge running down the bore. On an exhaust that ridge is a flow obstruction and a crack starter. Exhaust tube is made without it.

Half a Metre

Spark supplies this article as a 500 mm length. If a project needs more, order the number of pieces you need — there is no half-length or cut-to-size version, and joining two lengths is one more weld than a longer piece would have needed.