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While trying to answer Why static rope rather than webbing for toprope anchors? I immediately thought about splices in long pieces of webbing. For example, REI says that spools of Blue Water webbing may not be continuous, although I cannot find a reference on Blue Water's site.

I haven't worked with spools of webbing in a long time. My recollection is that a spool typically had 3 or so splices that were marked with tape an a pin. We use to cut around them, when making shorter slings. I do not remember how much space we left. My recollection was that apart from the pin/tape, there was no visual indication of the splice.

I cannot find any information about splices. I guess I have 4 related questions.

Do spools of webbing still have splices?

How weak is the splice?

How big is the section of weakness?

What do splices look like?

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+100

Do spools of webbing still have splices?

Yes. As Paul's answer pointed out, there was a well-known accident caused by a climber purchasing webbing with a tape splice in the middle.

Furthermore, multiple retailers have various warnings that spools may contain up to three sections (ie, two splices) per 300ft spool of 1in webbing.

http://www.cmcrescue.com/equipment/tubular-webbing/

Note: Military standards allow for up to three sections per spool.

http://www.strapworks.com/Flat_Nylon_Webbing_p/fnw1.htm

For most webbing the maximum continuous length is 150ft, after which a new roll is started.

How weak is the splice?

It's just two pieces of webbing taped together. The tape's stickiness is unknown, so it should be considered to have an effective breaking strength of 0lbs (0kN).

However, in actual tests (slide 13) by Rocky Mountain Rescue Group, tape splices break around 25lbs (0.11kN):

Result 1 : Adhesive failure, tape intact, webbing pulled out, 20-25lbs (0.08-0.11kN).

Result 2 : Tape tore (see photograph), adhesive held, 24-28lbs (0.10-0.12kN).

How big is the section of weakness?

Presumably only the tape-covered portion of the splice is effected.

What do splices look like?

Like this:

picture of spliced webbing

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    Would love to see a splice before breaking.
    – StrongBad
    Commented Apr 6, 2016 at 18:21
  • I suggest adding a sentence to the taped strength number of 0.11kN in the likes of: "This strength is just enough to maybe hold a person statically, but will break on the slightest additional load." Just to add a warning in prose alongside the number.
    – imsodin
    Commented Apr 7, 2016 at 6:34
  • There are also stitched splices - bethandevans.com/pdf/OnRope.pdf
    – Russell Steen
    Commented Apr 7, 2016 at 12:55
  • @RussellSteen stitched splices are different and I do not think are ever used on a spool of webbing. A stitched splice, for example, would be used in place of a water knot to create a loop.
    – StrongBad
    Commented Apr 7, 2016 at 13:54
  • @StrongBad -- A couple of sites I read indicated that stitches were sometimes used in "factory splices", but I'm hardly an expert :)
    – Russell Steen
    Commented Apr 7, 2016 at 13:56

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