What Does Protective Clothing Seam Types Mean?
Protective clothing seam types are types of garment seams that are suitable for use in personal protective equipment (PPE).
They differ from non-protective seams due to their mechanical strength and their ability to prevent various substances from bypassing the protective garment through gaps in the clothing seam or through degradation of seam integrity.
Safeopedia Explains Protective Clothing Seam Types
There are multiple types of protective seams available for use on protective garments, with many protective seams being more labor-intensive to produce and having greater material costs than less-protective seams.
Four common categories of protective seams (by increasing level of protection) offered by protective clothing manufacturers include stitched or “serged” seams, bound seams, stitched and taped seams, and stitched and double-taped seams. These seams are used for the six different levels of chemical suits defined by the European Union’s EN 943 standard or the four levels defined by the National Fire Protection Agency’s 1991 standard.
The suitability of a given seam depends on the hazards present in the area. Serged seams can be more elastic and provide superior breathability compared to taped seams, and therefore they may be an ergonomically superior choice if high-level chemical resistance is unnecessary.
Serged seams are regular seams of two pieces of material sewn together via thread that are interlocked around the edges of the material. The seam can face the internal or external surface of the protective suit. Additionally, the external stitch provides better particle filtration, but it is more vulnerable to abrasion. This seam provides mechanical strength, but it does not provide a full barrier to penetration by hazardous chemicals. It is suitable for basic protective suits and coveralls that provide light splash and dry-particle protection (EN 943 Type 5 and 6 suits).
Bound seams are seams also used in Type 5 and 6 protective suits. They are sewn into a folded strip of binding material that has similar or better chemical-resistant properties to the underlying seam. Bound seams provide superior liquid and particle repellency compared to serged seams, but they are also not liquid-tight.
Taped seams use tape as a barrier to seal off any gaps in the suit. The tape is thus chosen for its chemical resistance and impermeability. A complete seal is accomplished using heat or ultrasonic sealing.
Stitched/serged and taped seams, also known as over-taped seams, are stitched seams that are sealed under a layer of tape. This type of seam is liquid-tight, and it is therefore suitable for use in Type 3 and 5 chemical suits.
Double-taped seams are taped on both sides of the seam and are used in gas-tight Type 1 and 2 suits. Multi-layer tapes can be used to create “triple-taped” seams.
Some garments also offer “no-seam” designs for Type 1 and 2 suits. These are welded seams created when two pieces of material are fused together by heat. Seamless designs are also seen in various knit protective gloves, such as nitrile gloves.