Safety Anchor loading over vessel manway

[Boiler106]

Are there any OSHA provisions that allow an anchor meant for a winch to lower a man into a confined space, say a vessel, to be rated for less than 5,000lbs?

im fairly certain city crews arent using tripods rated for 5,000lbs when working over manholes for sewer systems.

Thoughts?

 

[CANPRO]

Where is the project located? In Canada, there is a code provision (can't remember which CSA standard, there are a few you need for fall arrest design) that allows an engineered anchor point to be designed for 2xMAF (maximum arrest force) which puts you more into the 2x900 = 1800 lbs range for design.

 

[azcats]

There's a lot of verbiage and caveats in OSHA, but the relevant text may be:

1910.140(c)(13)(i)
Capable of supporting at least 5,000 pounds (22.2 kN) for each employee attached; or
1910.140(c)(13)(ii)
Designed, installed, and used, under the supervision of qualified person, as part of a complete personal fall protection system that maintains a safety factor of at least two.

Note the 'or'. Not sure of its exact applicability to your situation.

 

[TehMightyEngineer]

im fairly certain city crews arent using tripods rated for 5,000lbs when working over manholes for sewer systems.

Often those are not fall arrest but rather confined entry rescue systems.

Ian Riley, PE, SE
Professional Engineer (ME, NH, VT, CT, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[JLNJ]

OSHA has similar provisions to those noted by CANPRO, whereby you can design for less than 5000#.

 

[TLHS]

A winch isn't fall arrest. Is there a situation where a fall could happen on the line? This is a fundamentally different situation. I'm sure there are OSHA style rules or guidelines somewhere. I'm not sure what they are though. Looking at man rated winches, they're rated more in the few hundred pound range rather than thousands of pounds.

 

[TLHS]

However, clicking on random products used for for confined space rescue, they seem to be rated generally for 5000lbs. So maybe that's what's used in general.

http://www.capitalsafety.com/caadmin/Pages/Search.aspx?prodCatId=11#2

 

[Geoff13]

My knowledge is more about fall arrest and anchors, so I can't speak too much about your winch.

I do recall once needing to specify a winch for rescue, and most are not man-rated. I suspect that material handling winches have a safety factor of 2 or 3 whereas I'd assume it would be more like 5 or 10 for a man-rated winch. The same safety factor should apply to the anchor as well.

For a fall arrest anchor, the US rule would be as noted by azcats, but in Canada each province has it's own rules. Many still use 22 kN (5,000 lb) for non-engineered systems, but Alberta has been modernised to use 16 kN (3,600 lb) for non-engineered systems.

For engineered systems the rule is 2xMAF, as noted above, but there are energy absorbers available for heavy workers and large falls that have a MAF of up to 8 kN (1,800 lb) and thus the anchor should be good for 16 kN (3,600 lb) in general.

If you want to use a lower anchor strength, then ask yourself if you have the needed control over the use for the life of the anchor to take that risk. When I design temporary HLL's for our in-house constrution workers I write a 10 to 15 page instruction manual for how to properly install and use the system, and I'd still get questions where the field was thinking of using the HLL in another way.

Whatever load you settle on, remember that for fall anchor purposes, this is the required failure load. You shouldn't just use this load in a standard Code calulation as that will add on another factor of safety and the anchor will be overdesigned.