SEAM CONSTRUCTION AND PERFORMANCE Garment seam design and quality is a very important consideration. All protective garments employ seams in their construction and due attention must be devoted to ensuring that the seam technology employed is up to requisite standard. It is not enough for a garment to be manufactured using the best barrier fabric if the seams are weak or leak. Different seaming confi gurations and connection systems are available which provide the necessary strength and impenetrability for different hazard and usage situations. The same considerations apply to closure systems such as zips and storm fl aps, and to garment interfaces and boundaries in the neck, hood, wrist and ankle areas.

All Category III chemical protective clothing must undergo a seam strength test as well as the relevant whole suit inward leakage test. Tight, reliable seams are an absolutely critical element in the overall barrier protection performance of a garment therefore when selecting a garment, it is important to verify the seam performance in addition to the fabric performance. Just because a seam is tight doesn t mean that it is impermeable and vice versa. Stitched seams on their own, for example, are never so fully tight that gas or particulates cannot penetrate. By properly overtaping a stitched seam, however. it can be made as tight and strong as the parent fabric material.


Type 3/4

Type 5/6

BOUND SEAMS Seam construction leaves the needle holes visible. Construction is unlikely to offer permeation barrier equal to the fabric.

Figure 9. Three types of seam construction.

STITCHED SEAMS Stitching offers good balance between seam strength and seam barrier.

STITCHED & OVERTAPED SEAMS Seams can be stitched and overtaped. The tapes used for DuPont products with this type of seam offer a barrier equal to that of the fabrics.

Annexe 5

Source: DuPont.