The AAR has required a crimp type sealer for steel strapping seals for a long time.  The reason is to strengthen the weakest link.  Your steel strapping is always weakest at the joint, or the seal.  A good notch type pneumatic sealer like the RCNS2-114 only gets a 70-80% joint efficiency.  That means you lose 20-30% of your strength at your 114P seal.

Crimp type pneumatic steel strapping sealers like the NSP-1435 can get a 95% joint.  The key is using multiple seals. Railroads like 2 or 3 seals, each crimped 2 or 3 times.  Typically 1.25 inch steel strapping gets 3 seals with 2 crimps each.  2 inch steel strapping gets 3 seals with 3 crimps each.

The strongest AAR steel strapping out there is 2 inch x .044 inch.  The only way you can seal is with a crimp style sealer.  We like Signode’s NS-250-65L best.

Notch type sealer are generally faster and easier, but there is not question that crimp style is stronger.  The most demanding AAR applications require crimp type sealers.