Lifting hooks fabricated from steel plate

Excelent answer Ozzb,

I have had several jobs where that type of site-rigging was used, at least one of which I walked off of. Just one injury or loss of life will be more expensive by far than getting the proper gear in the first place. On the jobsite is no place to test whether something will work or not.

Only the slightest of over-cut of the inside corners of the shape could accelerate shear failure under load, a hook might work several times and then suddenly give way. For such a run-of-the-mill task, it is extraordinary that "home made" equipment has even been considered. You have certainly made the right decision, I would review everything on the site as there may well be other inappropriate short-cuts being used.

You are absolutely correct.

Forging also refines and defines grain flow; cutting from plate may actually leave the section perilously dependent on center segregation area from initial solidification, depanding on how cut.

Stress risers from cutting have already been mentioned.

Fianlly, WHy tensile strength and not yield?

If improperly "balanced," when placing on the payload, one hook can yield (stretch) thus leaving more load on the other(which could then stretch) Stretching meanselongation whichmeans loss of transverse section (necking) which means less strength which means ...

You get the picture. all posters so far validate your concerns.

BTW Was the plate UT and eddy current tested to assure freedom from deleterious surface and internal imperfections? or was it "just plate?" Carbon level? If it was high carbon, and torch cut, was it tempered or is possibility of untempered martensite lurking as a brittle "switch" to cause failure under "shock" loading or impact? Can alsoform martensite by heavy handed grinding...

Our first duty is to do no harm; as engineers we have a duty to protect thepublic.

milo"Danger will robinson"

Fabricated from Plates lifting Ladles 200Ton -- :

These hooks I saw being actually inService at a large Steel Plant 35 Years back.

Forging also can go wrong.

• Design the Hook with right STEEL and fabrication procedure
• Load Test at 150%>200% at routine schedule Ground level max 1m up.
• Inspect Yields carefully after every Test--keep a log /Entry.
• Inspect suspect Stress concentration areas with NDT -- Ultrasonic/Dyein between overload tests

Are there not standards for rigging equipment that specifies the requirements for capacity (certified) and also would non-standard equipment have to be Engineer approved (and stamped docs) ??

That just reeks of disaster. Who is looking after OHS on your site? There are companies out there that specialise in this type of equipment Try Bullivants.

Good answers by everyone. No excuse at coroners inquest if fatality occurs. Ask contractor if they would have a picnic with their family under the suspended load.

Sleep well at night. Do the job safely. Might not be your people, but now your responsible for them.

I think you did the right decision of stopping the job. apply engineering principle to our job. it makes a big difference

You are 100% correct.

You and anyone else who was aware of the use of these ad hoc devices would be liable to criminal prosecution.

But most importantly, someone could get injured perhaps fatally so. An accident not only has consequences for the person who has the accident but also for his/her family. When the consequences are thought about, you have an irrefutable moral and legal argument. Never back down.

To be quite honest, you should be proud that you have done the right thing.

The Hooks described by you are called laminated hooks which are still used in steel industry. You should test these hooks at twice their SWL. Latter on test them radiographicaly for any internal defects. You can also check for surface defects with dye pentration test. If it passes all the tests then there need not be any concern. What is capacity of each hook?. Why contractor has selected such hooks where as he could buy standard forged hooks?.

If in doubt...

You did the right thing. As the safety manager it is your job to question, and if you had the question in the first place, then something is possibly being done incorrectly. If it failed, could you live with someones death on your conscious? This stoppage of work could have even cost you your job in some areas, but would put you in a prime position for hire with another company. I wish our safety manager was as observant as you.

With todays technologies, there are still to many short cuts being taken to save a dollar.

How long has the "C" type lifting hook you are now using been used? If it has worked for some time, then I would submit that it has passed the test of time. However, if you still feel uncomfortable, put a little more steel in it. Go to 30mm steel plate. This isn't very scientific but it sure is a lot cheaper than redesigning the wheel. It should bolster your confidence by at least 50% (more steel).

On the other hand, if these hooks are shipped with the product and require replacement, then you may be justified in trying to "engineer" the hooks. That way you get the best product at the least cost.

I strenuously but respectfully object to this conclusion.

This is a commercial application. There are legal and ethical responsibilities to do things right.

Consensus and agency standards as well as Laws define what is right.

Cheaper is NOT the ISSUE.

Human safety is.

There are agency standards that deal with this

ASME

http://catalog.asme.org/Codes/PrintBook/B3010_2005_Hooks.cfm

http://catalog.asme.org/home.cfm?TAB=Designator&DESIGNATOR=B30.20

Volume B30.20 includes provisions that apply to the marking, construction, installation, inspection, testing, maintenance, and operation of below-the-hook lifting devices, other than slings, used for attaching loads to hoist. The devices are arranged in five chapters as follows:

Chapter 20-1: Structural and Mechanical Lifting Devices

milo

The applicable US standards in this situation would most probably be ASME B30.20 Below-The-Hook Lifting Devices, ASME BTH-1 Design of Below-the-Hook Lifting Devices and AWS D14.1/14.1M Specification for Welding of Industrial and Mill Cranes and Other Material Handling Equipment.

Curved beam theory is not necessarily as straight forward as one would think.

Please look at purchase from a reputable manufacturer.

RHREID; I would recommend that you insist on the application of an industry standard such as ANSI/ASME B30.10 and require the hooks to meet or exceed these requirments. Then I would require the load test data and an inspection program to assure the hooks continued integrity. Something like

1. Rigging hooks that are not permanently installed in a sling assembly shall be visually inspected for the following deficiencies before use:

a. Distortions such as bending, or twisting exceeding 10 degrees from the plane of the unbent hook

b. Increased throat opening exceeding 15 percent

c. Wear exceeding 10 percent of the original dimension

d. Cracks, severe nicks, or gouges

e. Hook attachment and securing means.

2. Rigging hooks shall be inspected as a part of the slings to which they are attached.

Good luck wdwrkr

Ask the person who suggested that to stand under the concrete when its lifting. If they refuse then it doesn't pass. Ask him/her to bring the family.

Plate are usually cut with plasma, laser or waterjet. Plasma and laser will heat up the edge and create extra stress on the material. It'll make the surface brittle and easy to crack under load. To make it worse, all 3 process doesn't produce a smooth surface. Those rough peak and valley will increase stress concentration. Very bad combination.

1. An engineer's job is to get the work done, and not to stop it. Stopping of work is best left to the unions!

2. There is nothing wrong per se in using hooks fabricated from steel plates.In steel plants, we have seen fabricated steel hooks ( C-shaped) being used for lifting steel ladles, and no mishap owing to failure of such a hook has been reported in 36 yrs of my service in integrated steel plants.

3. However, if you give a sketch of the hook and the load , it will help to examine the case better.

As MILO said, "Our first duty is to do no harm; as engineers we have a duty to protect the public."

As far as "An engineer's job is to get the work done, and not to stop it. Stopping of work is best left to the unions!" ... umm ... no disrespect saran369, but that kind of reasoning is the kind of uninformed and irresponsible logic that I have had to deal with for many years. I will ABSOLUTLY stop a job, for just such a reason. Worst case scenario must be considered 100% of the time. And loss of life or limb is the ultimate worst case scenario. There are no second chances if something goes wrong. And "I'm sorry" to surviving family members usually just doesn't really cut the mustard.

The bottom line, to which there can be no argument is .. You have to be CERTAIN. Period. Full stop. Being paranoid and over-conservative is one thing. But that does not mean the same thing as being certain.

By all means, stop the job and take the necessary steps to be certain. And feel good and justified about your decision.

Totally agree with you OoBE. It might delay a job for a day while the lifting hooks are inspected. But it's worth it.

I work in the mining industry. A couple of years ago we had a death because procedures and standards were compromised over time. "She'll be right mate", attitude. For the sake of waiting 1 hour it cost a man his life. It was finally worked out that his death, cost the company $73 Million in lost production, fines, and compensation etc. Is one man's life worth $73 million? Of course the answer is NO. It's worth a hell of a lot more. Actually a person's life is priceless. Literally. And it's about time that alot of companies realise that.

WOW An Interesting Subject

In my opinion, Sorting Hooks are commonly made with a proper identification from the manufacturer and has name or logo, load rating/size and traceability.

Since you referred as "Job Made" or fabricated, Is it a flame cut? If so, is this performed by competent person following a qualified procedure that meets your county industrial standards or say AWS ASME requirements? Or atleast the engineer take into account before certifies.

You may face real challenge in here if the certifying bodies does not consider the long run effect of the tool and have just based on the Calculated Safety Factor and initial load test.

I would also check from the contractor about the hook's performance in relation to ductility, fatigue and impact properties.

This is due to the fact that most if not all "Home Made Lifting Gears" can fail without warnings!

Lifting Hardware Manufacturers make their product from good quality of materials, especially forged, heat treated and well engineered.

And should the hardware ever breaks, I would imagine on the course of investigation the cause will comes back to fact that is still a man made or home made regardless who "Engineered" or "certified" it.

"If you think job made lifting gear is OK what safeguards should I insist on?" I would then insist onto the site line management committee to decide, approve and have a common standard on the safe use of "HOME MADE"!

In my construction site "home made is a home made". I would then conclude that WoRkerZ will fully vote full mark with your decision for being objective for the sake of workers safety involved in this operation. I just wish more Safety Managers like You in Construction Sites!

I agree, I had experience using a shop fabricated tool for lifting concrete pipes for huge drains and the hook snapped diaagonally from the C hook made from steel without warning of elongation of deformation that has safety factor of 8 from yield calculation! It was just lucky no one was harmed so we ban home made lifting gears. I would say this is should be a wake up call to management!

The most important factor in what you said is not the safe working load limit of those hooks, is the safety regulation. You can lift something with a fibre rope over a tree branch, you can do that in your back yard but is illegal to do that in a company.

All hooks used for rigging and lifting usually must be forged alloy steel with the safe working load stamped in it. The contractor does not have to provide you calculations, he has to provide you standard and profesional equipment. He is cheap. Let him go. If you stoped him you did the right job.