In LNG cryogenic engineering, the fixing method of the elastic felt directly affects the integrity, continuity, and long-term stability of the insulation layer under cryogenic conditions of -160℃. Unlike conventional insulation materials, the fixing design of LNG elastic felt must adhere to the core principle of "not generating constraint stress and allowing cryogenic shrinkage." The following analysis, from an engineering practice perspective, examines common fixing methods for LNG elastic felt in engineering and their key points.

First, it is important to clarify that LNG elastic felt should not be fixed using strong constraint methods. During cryogenic operation, pipelines and equipment undergo significant cold contraction. If the elastic felt is rigidly compressed or fixed by spot welding or bolts, it is highly susceptible to tearing, bulging, or joint separation at low temperatures. Therefore, the basic principle of fixing is "positioning without locking."

The first common method is adhesive fixing.

On the surface of pipelines and equipment, cryogenically applicable adhesives are typically used to fully or partially adhere the elastic felt. This method primarily serves to prevent slippage during construction and ensure adhesion, rather than bearing the structural loads during operation.

During bonding, avoid stretching the material and ensure the elastic felt adheres to the substrate in its natural state, allowing for deformation space to accommodate low-temperature shrinkage.

The second method is non-rigid binding fixation.

In horizontal or vertical pipe construction, fiberglass tape, stainless steel flexible tape, or specialized binding tape are often used for auxiliary fixation. The purpose of binding is to restrict material displacement, not to compress the insulation layer.

The binding spacing should be uniform, and the tightness should be such that it does not compress the thickness of the elastic felt, avoiding localized compression that could reduce insulation performance or create cold bridges.

The third method is layered staggered fixation (multi-layer structure).

In LNG pipelines and storage tanks, elastic felt typically employs a multi-layer insulation structure. Each layer can be bonded independently or lightly bound, and the joints of each layer should be staggered.

This method can distribute low-temperature shrinkage stress, preventing stress concentration in the same location and improving the overall system stability under cryogenic conditions.

Fourth, the indirect fixing effect of the outer protective structure.

After the elastic felt is installed, the system typically includes a moisture barrier and a metal outer sheath (such as aluminum or stainless steel). The outer sheath should not directly compress the elastic felt; instead, it should provide overall containment and protection for the insulation layer through a well-designed gap. The fixing points of the outer sheath should have allowances for sliding or expansion to accommodate thermal displacement changes under cryogenic conditions.

Fifth, fixing of irregularly shaped parts and vertical structures.

The elastic felt is more prone to displacement at elbows, valves, flanges, and risers. In engineering, a combination of "adhesion as the primary method and light binding as a secondary method" is usually adopted, while reasonable segmented cutting reduces the concentrated effect of the material's weight on the fixing points.

Finally, it is important to emphasize that the fixing method for LNG elastic felt must be considered in conjunction with the cryogenic design. The goal of fixing is not "the tighter the better," but rather to ensure that the material can freely contract and shrink during cryogenic operation without falling off or damaging the continuous insulation layer.

In summary, the main methods of fixing LNG elastic felt in engineering are bonding, non-rigid binding, and external protection restraint. The balance between structural stability and low-temperature adaptability is achieved through flexible fixing, which is the key to ensuring long-term reliable operation in cryogenic engineering.