Vertical Rescue Hardware

Hardware for Vertical Rescue includes all the mechanical bits and pieces used in a rescue system: karabiners, ascenders, pulleys, rigging plates, decenders, etc.

Some services have protocols in which operators must remember the Safe Working Loads (SWL) and/or Minimum Breaking Loads (MBL) of every piece of equipment. That is not my personal experience or preference. I strongly believe in the KISS principle when lives are at stake, so I will discuss a much simpler approach - that used by the service I used to operate with (and also used by many others).

What SWL for Hardware?

The protocol and state standards to which I am used to operating is that all hardware must meet or exceed a MBL of 2000 kgf (20kN). The industry standard for the Safety Factor (SF) on hardware is 5. So the SWL of every piece of VR Hardware must meet or exceed 400 kgf (4 kN). There may be other strength requirements specific to different types of hardware. These will be discussed in the appropriate sections.

So
SWL = 400 kgf
SF = 5
MBL = 2000 kgf
for all hardware.

Now while the protocol of some services requires that the VR operator knows the exact MBL or SWL of every bit of gear, I do not subscribe to that. My philosophy is that you only buy gear that meets or exceeds the minimum standard (in this case MBL = 2000 kgf or more), and once bought it is considered to meet the standard. i.e. MBL = 2000 kgf. If its actual MBL is greater then we ignore the difference and treat that as extra safety factor.

The point here is to keep it simple! Vertical Rescue Systems can get all too complicated very quickly - let's not make it more complex than it needs to be.

The following are notes on each specific type of VR Hardware:

Karabiners	Descenders
Ascenders	Pulleys
Belay Devices	Anchor Hardware
Miscellaneous Hardware

Manufacturers Stamps

Should the strength of the hardware be stamped into the gear? Some people will argue that "clean skin" equipment (i.e. those without load ratings marked on them) are acceptable in rescue. The argument goes: "We know they were strong enough when we bought them, otherwise we would not have bought them. So it's OK." That's fine, I don't have a problem with that argument for personal gear where the person who uses it is the person who bought it. But do you really know what its strength rating is or are you taking a salesman's word for it? Do you have a trail of evidence right back to the manufacturer? Consider what happens when different rescue units combine in a large rescue operation or exercise. Invariably people will be using other people's gear. A large amount of trust is required to use gear that you don't know the history of. Manufacturer's load rating stamps on the hardware takes one element of uncertainty out of the situation. So I recommend all VR Hardware should display the manufacturer's load rating stamp(s) as well as the manufacturer's name.

Marking and Identification

There are many ways to mark a hardware for identification. There are pros and cons to each of them.

Engraving

Engraving is permanent, won't wash or wear off (easily!) and so is often considered for marking and identification of gear. The problem is that engraving removes metal. It doesn't remove much, but even a little bit in a highly stressed area could be disasterous. In a highly stressed area, the engraving may just provide sufficient stress concentration factor to affect the fatigue life of the piece of gear - to bring it down into the range of the number of loading cycles that the gear might resonably be exposed to. So it may not fail stright away... it might seem OK for years before it fails.

Now don't go banning engraving. It's OK if done in the right place: somewhere that's low stress.

Examples of low stress areas suitable for engraving:
• Karabiner gate sleeves, or in some case the gate, but never the spine of the krab!
• The very end of the karabiner inside the gate (e.g. some Stubai krabs have a flat end suitable to engrave up to 3 letters into)
• The large end of a pulley cheek (not the krab end)
• safety gates of descenders
• The very end of the J groove in mechanical ascenders, the end of the pin in Gibbs type ascenders, or the plastic hand grip on some handled ascenders.

Painting

Painting often isn't as permanent as engraving, but it doesn't affect the strength of the hardware either. It still needs to be thought about carefully, however, because paint can hide cracks. So my recommendation is don't paint the whole item, or indeed any highly stressed parts. Use a paint pen, or nail polish to mark low stress areas (refer to the examples above for engraving). Painting offers the flexibility of using both colour and symbols for marking and identification.

Stickers, Tape and Heat Shrink

Stickers, tape and heat shrink are probably my least preferred option. The offer a lot of the disadvantages of painting, but one problem that heat shrink is particularly susceptible to is moisture under the heatshrink which can result in corrosion in the long term. I have never experienced it, so maybe I'm just being biased there. The other thing about heat shrink is it must go right around the object it is attached to and this can serious limit the ability to inspect the tiem for cracks or other damage.

Back to Al's Vertical Rescue Notes