CSA Z150 Safety Code: Why Does it Matter?
CSA Z150-11 is the newest release of the Safety Standard on Mobile Cranes. The last addition was released in 1998 so we have been due for an update to this code for some time now. But why did it take until 2013 to write a review of a code released in 2011? I believe most of the industry are late adopters of these codes, not to mention that no one has written about it yet so I figured someone should. CSA Z150 is an important code because although the CSA code groups are a voluntary standards this specific one has been adopted by OH&S legislation making it legally binding in Canada. It is also a comprehensive guide for being safe while constructing, inspecting, testing, maintaining and operating mobile cranes.
Some Small Changes That Might Interest You:
- Under the Z150-11 all cranes in service will be required to have some form of load-indicating or limiting devices not just cranes manufactured after 1999.
- Minimum diameter of hoisting drum has been changed for 18 to 15 times the drum diameter
- If the efficiency of the end connection is less the 80% this must be factored in when specifying the wire rope.
- Boom pendent or standing rope safety factor has been raised from 2.5-3.0
- Substantial changes with using rotation resistant ropes.
- All swaged, compressed, screw type or poured socket end connections shall be proof loaded to 50% of rated breaking strength after installation rather then just being “of adequate strength”
- Detailed test records of rope installation on mobile cranes needs to be kept and recorded in the log. These records need to indicate proof load if applicable, description, size, manufacturer and supplier etc.
- Aluminum sheaves are no longer allowed.
- Loose and turn-able bolts no longer need to be replaced along with the ones next to it but now the operator/inspector needs to refer to the crane manual.
Changes to the Annual Inspection Requirements
Much to my surprise CSA-Z150-11 changes (or more accurately clarifies) some of the inspection intervals on mobile cranes. The two major changes are:
- The requirement to have the non-destructive testing completed on the interior welds of a telescopic boom at least every five years
- To require full tear down as per manufactures recommendations instead of every 10 years
I had interpreted Z150-98 as requiring mag particle on the ends of the telescopic boom as part of the annual structural inspection which has been changed to at least once every 5 years. I am not sure I agree with this change given the trade off between additional safety and the additional cost of a more thorough inspection. When you have an inspector right there doing the inspection it makes sense to me to have him extend the boom and complete the job. Having a third inspection interval will also make it difficult to track when you services hundreds of cranes. I am also not sure how this will be effectively enforced as record of this inspection won’t necessarily be attached with the annual inspection.
The change for requiring a full tear down once every ten years to “as per manufacturing specifications” is a very interesting change in my mind. First off its a hassle for engineers and inspectors to be versed in every crane manual they might encounter. These manuals are often wildly different from manufacture to manufacture and can sometimes be hard to get your hands on (especially in the time frame of most jobs). I can certainly relate to the Canadian Standards Association not wanting to over rule a manufacturers maintenance interval if it is substantially less then ten years, say, every three years. However, there will be a lot of upset crane owners as well as cranes not in compliance if the rules are so specific to the crane that they are hard to comply with or enforce. In light of these new changes I will be reviewing as many crane manuals as I can get my hands on for this requirement as well as continuing to recommend a full tear down at the very least once every 10 years.
Some additional detail has been added to CSA Z150-11 regarding the annual inspection. It gives substantially more points to check on the block and hook above and beyond the standard magnetic particle examination. It also writes out the requirement of having a written copy of an inspection report along with the engineers opinion if it is structurally sound. A copy of the report needs to be inside the crane. These few changes seem to be inline with what the current industry standard and is a nice addition to the code.
New Testing Requirements of Z150-11
CSA Z150-11 has added some detail to the section on testing cranes. This is a fantastic addition to the code as it certainly adds detail and a few quality points regarding testing cranes. It outlines that all new crane installs need to be function tested and load tested to an extent that proves compliance with Z150. I am sure most companies test the functionality of their crane installs but is everyone load testing their cranes? Further more, it also outlines in the cases of re-manufactured cranes or repairs to structural components, load testing should take place and should not exceed 110% of manufactures load rating.
More work can be done to address or standardize failure modes or failure criteria during testing. Sparta Engineering has partnered with Global Crane Inspection and together we have developed a fairly detailed load and stability testing procedure based around what we feel is correct but it is different then what other inspection companies are doing.
THE STRUCTURAL SUBFRAME:
After writing this article and doing an in-depth review of this code, it still isn’t clear if the structural modification or repairs that are referred to throughout the code cover the subframe of the crane. Most companies know to slow down and do a repair to a boom correctly but is everyone taking the same careful approach to the subframe? In Alberta it seems that the crane company will ship a crane unmounted to a shop who will sell the crane and mount it to a custom fabricated subframe.
The current industry standard in Alberta is for these subframes to be built from experience (and a little trial and error) and often don’t involve any engineering. Now if you were to ask anyone, especially on a larger crane, if the subframe is “structural” I am certain they would say yes. But that leaves me to wonder why engineers are not stamping subframe design and/or crane mounts and why the industries treats the subframe differently then the boom?
Some links that might be useful: