A gas strut can look fine at first glance and still fail early when its material is wrong for the job. A toolbox on a ute, a boat hatch, a caravan locker or a washdown-area cabinet all face different combinations of moisture, salt, dust and vibration. This stainless steel strut material guide explains what stainless steel does well, where it has limits, and how to specify a strut that will last in the conditions you actually work in.
What “stainless steel” means on a gas strut
Not every strut described as stainless has the same level of corrosion protection. A gas strut is made up of several parts: the pressure cylinder, piston rod, end fittings, seals and internal components. The cylinder and rod are the surfaces most exposed to the environment, but end fittings, brackets, pins and mounting hardware matter just as much.
A fully stainless steel gas strut generally uses a stainless cylinder and rod, with stainless end fittings where specified. This is the preferred arrangement for marine equipment, exposed outdoor installations, food-processing areas, washdown environments and machinery that operates around chemicals or persistent moisture.
Some struts use a painted or coated steel cylinder with a plated rod. This can be a sensible, cost-effective option for dry internal cabinets, protected vehicle compartments and equipment that receives regular inspection. It is not the same as a stainless assembly, and it should not be treated as one when the strut will see salt spray, standing water or regular chemical cleaning.
Stainless Steel Strut Material Guide: 304 vs 316
The two stainless grades most commonly considered for exposed gas strut applications are 304 and 316. Both offer far better corrosion resistance than ordinary carbon steel, but they suit different levels of exposure.
304 stainless steel for general exposure
Grade 304 is widely used for general-purpose stainless hardware. It performs well in clean outdoor settings, sheltered vehicle and trailer applications, and industrial environments without a high salt or chemical load. For a canopy door, external cabinet or machinery guard that gets wet occasionally and can be cleaned, 304 may be suitable.
Its limitation is chloride exposure. Chlorides are found in sea air, salt spray, road grime near coastal areas and some cleaning chemicals. Over time, 304 can develop surface staining or pitting in these conditions, particularly where water sits around threads, ball sockets or mounting brackets.
316 stainless steel for marine and high-corrosion work
Grade 316 contains molybdenum, which improves resistance to chlorides. That makes it the usual choice for boat hatches, bait boards, marine lockers, coastal equipment, offshore installations and applications exposed to regular saltwater contact.
For many Australian coastal and marine jobs, 316 stainless is worth the extra upfront cost. Replacing failed struts on a hard-to-access hatch, machinery enclosure or heavy lid costs more than the part itself once downtime, labour and safety are factored in.
However, 316 is not corrosion-proof. Salt deposits left on the cylinder or rod can still cause tea staining and surface pitting, especially in crevices. Stainless parts need occasional fresh-water rinsing and cleaning if they operate in a saltwater environment.
Match the strut material to the complete installation
A stainless gas strut fitted with mild steel brackets can still produce corrosion problems. Moisture collects around mounts, fasteners and ball studs, and dissimilar metals can accelerate corrosion where they remain wet. The strut may be serviceable while the bracket or mounting point weakens around it.
Where corrosion resistance is a priority, specify compatible stainless ball studs, brackets, pins and fasteners. Grade 316 hardware is usually the better match for a 316 marine strut. If stainless mounts onto aluminium, as it often does on boats, caravans and fabricated canopies, use suitable isolating washers or barriers where practical. This helps reduce galvanic corrosion caused by moisture between unlike metals.
The rod surface deserves particular attention. The rod passes through the seal every time the strut opens and closes. Scratches, dried salt, abrasive dust and paint overspray can damage the seal and lead to gas or oil loss. Stainless improves corrosion resistance, but it cannot compensate for a rod that is regularly knocked, bent or contaminated.
For most gas strut installations, the cylinder should be mounted above the rod when the strut is closed, with the rod pointing down. This keeps internal lubrication near the seal and supports longer service life. There are exceptions for specific designs and mounting positions, so check the strut specification where orientation is restricted.
Material choice does not replace correct strut sizing
A 316 stainless strut with the wrong force rating will still be unsafe or difficult to use. Material selection and mechanical specification must work together. This is especially relevant for heavy marine lids, machinery guards, caravan beds, toolboxes and custom access panels.
When replacing an existing strut or requesting a custom unit, record the following details:
- Extended length, measured centre-to-centre between the mounting points
- Compressed length and available stroke
- Force rating, normally marked in Newtons as N on the existing strut
- End fitting type, such as ball socket, eye, clevis or pin mount
- Mounting position and the angle of the strut through its travel
- Lid, door or panel weight, plus where its centre of gravity sits
The force rating is not simply the weight of the lid. A long, heavy lid can need less force when the strut mounts far from the hinge, while a lighter lid may need higher force if the mounting geometry gives the strut little leverage. Two struts may be required for a wide panel to prevent twisting, but adding force without checking the hinge and mounting structure can damage the lid or make it hard to close.
Temperature also affects performance. Gas pressure changes with temperature, so a strut can feel firmer in hot conditions and softer in cold weather. For machinery, refrigerated areas, high-heat enclosures or applications with frequent washdown, make sure the seal and operating-temperature range suit the service conditions as well as the stainless grade.
Common corrosion mistakes in strut installations
The most common mistake is selecting stainless for the visible cylinder but retaining rusty mounting hardware. The second is assuming a coastal location needs no maintenance because the strut is stainless. Salt remains salt, and it works into sockets, threads and narrow gaps.
Avoid using chlorine-based cleaners or harsh abrasives on stainless struts. These can attack the surface or leave deposits that encourage staining. A rinse with fresh water, followed by a wipe of the exposed rod with a clean soft cloth, is usually enough for routine care. Do not apply heavy grease to the rod unless the manufacturer specifically calls for it, as grease can hold grit against the seal.
Inspect the strut during normal servicing. Look for pitting on the rod, rust around end fittings, loose ball sockets, oil weeping at the seal, bent brackets and reduced holding force. If a pair of struts supports one lid, replacing both at the same time generally gives more even operation.
When a full stainless gas strut is worth specifying
Full stainless construction is usually justified where failure would create a safety issue, access problem or expensive maintenance task. Marine hatch covers, exposed trailer storage, agricultural machinery, washdown cabinets, coastal vehicle canopies and equipment used in mining or processing environments are common examples.
For an indoor office cabinet or a protected toolbox that stays dry, a standard coated strut may offer the better value. The right choice depends on the environment, expected service life and how easily the strut can be inspected or replaced. Spending more on stainless makes sense when corrosion is likely, not simply because the word sounds premium.
Before ordering, check the material grade, cylinder and rod construction, end fittings, force rating and measurements as one package. If any detail is uncertain, provide clear photos and the key dimensions to a strut specialist. That is the quickest way to avoid fitting a quality stainless strut to a job it was never sized or equipped to handle.
