Stainless steel and carbon steel corrode easily when in contact, but what about metal wound gaskets?

Stainless steel spiral wound gaskets can be used between stainless steel and carbon steel, mainly because they can effectively prevent direct contact between the two metals. This can reduce galvanic corrosion caused by electrochemical differences between metals. At the same time, metal wound gaskets generally possess good corrosion resistance and sealing properties, and can withstand certain temperature and pressure changes, thereby protecting the internal structure from damage. .

That’s not correct, right? The materials in contact with each other are generally of the same type; for example, the inner ring and the winding material are of the same kind, while the outer ring can use a different material.

The point you raised makes some sense, but in the actual design of composite gas cylinders, a more careful selection of materials for each layer is required. The following is a detailed clarification of this issue: **1. Typical structural layers and materials** – **Liner layer**: Usually made of high-density polyethylene (HDPE), nylon, or aluminum alloy; its primary function is to seal the medium (such as gas). It is completely different from the material of the winding layer. - **Winding reinforcement layer**: Made of carbon fiber/epoxy resin or glass fiber/epoxy resin composites, it provides high-strength support through fiber winding; it does not intersect with the lining material. - **Outer protective layer**: A polyurethane coating or rubber layer may be added to prevent scratches and provide protection against ultraviolet rays; its material is indeed different from that of the inner layer. **2. Technical analysis from a user’s perspective** – If the liner is mistaken for an “inner ring” and the wrap layer is regarded as “wrapping material”, there are fundamental differences between the two materials: the liner is a plastic sealing material, while the wrap layer is a rigid composite material. - "The concept of \"downgrading the outer ring\" is valid: low-cost polymers such as polyurethane can be used for the outer layer, as they are not subjected to stress and only need to provide basic protection. **3. Design logic verification** – Material coordination principle: The lining needs to be flexible to prevent cracking, the wrapping layer requires ultra-high strength, and the outer protective layer must be resistant to environmental corrosion; the material requirements for these three components are entirely different. - Cost control approach: Use low-cost materials only for non-pressure-bearing components (such as the outer coating), while high-performance materials must be used for the core structural layer (the winding layer). **Conclusion**: Part of your observation is correct—the outer layer may indeed use lower-grade materials, but the difference in material between the lining and the reinforcement layers is the key technical feature. Thank you for bringing up this detail that deserves in-depth exploration; it is very important for understanding the logic behind the layering design of composite materials. In practical engineering, such differentiated design of materials is precisely the key method to balance performance and cost. -

But the metal gasket itself is made of stainless steel; isn’t it resistant to coming into contact with the sealing surface of carbon steel flanges?

Corrosion occurs when these two materials come into contact under certain conditions; factors such as the contact surface and the duration of contact also need to be taken into account. If you’re concerned about corrosion with metal wound gaskets, you can use two matching stainless steel flanges, or wrap some PTFE tape around the gasket to isolate the contact surfaces. Welding of stainless steel and carbon steel is also permitted, with relevant specifications available for reference.