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Oilfield Gin Poles

My first interaction with gin pole design was on a project where Sparta was contracted to provide an engineered and certified pole design. At the time, due to budget constraints and customer demand, this project was limited to just an analysis of the structural elements of the pole itself and not system as a whole. This design was rated for 45-ton a load comparable to a dedicated crane carrier system. After the initial analysis it became very evident that a pole may be rated to lift a large load but otherwise has very few guidelines or regulations on its design or use.

Current regulations on gin poles are limited to a single paragraph reference in OH&S and the IADC guidelines published in 2010. Combined, these are good starting points for this industry but fall short in offering any real engineering or construction guidelines. They also do not go into any depth as to the proper use of the equipment or safety procedures during the planning and execution of a pick. For any one familiar with this equipment as well as current crane regulations it seems strange to me that on one hand, you have highly regulated crane industry governed by CSAZ150 with certification for operators, a well-defined safe operating procedure with safety equipment such as outriggers, load charts, load limiters and on the other hand you have a gin pole, which does a similar job in a completely unregulated industry with untrained operators and equipment that hasn’t necessarily been engineered.

In the past I have been approached by various parties regarding outlining some more in-depth safety regulations for this niche industry. I am very excited for the chance to be involved in the design and regulation of a product and industry that hasn’t been engineered in a long time, if ever. This is a proposal as well as a rough outline of what needs to happen in order to have an engineered certified pole truck. Following the proposal there will be the option of an advanced analysis package that will cover some of the more in-depth gin pole problems such as pick and carry capacity as well as stability parameters. Lastly, I will outline some of the possible programs that could be built around this piece of equipment.

Sparta’s History: Design for Manufacturing

Sparta Engineering was established in 2007 and grew out of an in house engineering firm at CBI-Manufacturing. Starting with three founding partners, Sparta has grown to a team of roughly twenty engineers, techs and support staff. Sparta maintains offices in Calgary, Linden, Grande Prairie and Toluca Mexico. The team of engineers at Sparta has a substantial amount of experience in engineering and designing oilfield related equipment and specializes in mobile and skid mounted equipment of all types. Through the use of modern engineering processes Sparta has successfully challenged the status quo and pushed the limits of what is possible in industries such as well servicing. Sparta’s flagship product line is a series of single and double truck mounted service rigs featuring an ultra-light and strong plate steel mast. Through the use of modern finite element analysis and a fresh approach to old problems, Sparta was able to design a new style mast and supporting structure light enough to mount to a standard purchased tandem steer, tri drive truck rather than a fabricated carrier. Designing a truck mounted service rig that is under period one weight regulations as well as meeting API4f has established Sparta as the leading expert in service rig design and engineering. On the crane side, Sparta has a line of engineered crane subframes for larger knuckle pickers that have proven to have great performance against that industry status quo. By utilizing FEA analysis and high strength material we have successfully reduced the weight of our subframes by around 25% while still maintaining the stiffness and at the same time providing an excellent level of confidence in both the end user and the manufacturer.

The Proposal:

General Free Body Diagram:

The free body diagram is the traditional engineering approach to structural design. During this part of the analysis Sparta will utilize all inputs consisting of dimensions taken off the truck and the desired hook load to calculated output reaction forces on the winch and wheels. This will be the basis of a calculator that can be used to apply the results of this whole analysis to any bedtruck design. The free body diagram will also be used to verify the accuracy and relevance of our computer models that tend to be more accurate but can also be irrelevant if not anchored with this style of traditional engineering.

Pole Analysis:

The second step in this analysis is to review the design of the pole itself. There are four components of the design of the pole: the structural element, the base pinned connection, the sheave pin and the tie back lines.

This will start with a free body diagram of the pole which should output lines sizes, sheave pin size, required cross section for the pole and pin size at the base of the pole. This will need to be verified and optimized through the use of finite element analysis which will allow us to specify material requirements and minimum safety factor required on this component.

Truck & Deck:

I believe the analysis of the truck and deck will be the most interesting component of the system. In this analysis we will specify the minimum cross section required for the section right under the pole as well as the minimum cross section between the pole and winch. It will specify winch tie down requirements, bed block attachment requirements as well as required welding procedures and standards. A review of acceptable style and size of mounting systems for the deck will also take place. This analysis will also go into specifying components on the truck itself such as minimum frame specifications, axle specifications and maximum axle/tire load and whether these are all in line with the required hook load.

Rigging:

The rigging section of this analysis will start with a comparison of safety features on winches. Some winches, such as the Tulsa intelliguard winch, have built in safety devices that could provide a high degree of feedback and safety in the field. The rigging analysis will use results from other sections of the analysis to specify minimum required working load and diameters on winch lines and tie back lines. Furthermore, it will review minimum sheave specifications regarding load as well as diameter and suggest a supplier of such a sheave. This section will also review the OH&S mention of a boom stop system to stop the pole from coming back over center if the load is suddenly released.

I suspect there is a large disconnect that will be found in this analysis between what is industry standard and what the proper equipment matched to the required hook load will be.

Advanced Analysis Package:

There are several advanced analyses that should be offered within this proposal. These analyses are not ultimately required to complete the structural analysis of the unit, but, are needed in order to give proper field instructions based on informed engineering decisions. I have separated these out into a second section because these are in-depth and involved.  This analysis will take time and special expertise to complete.

Load and Stability Analysis #1

This analysis is to explore the maximum lifting capacity as governed by stability when lifting a load straight vertical off the rear of the truck. It is fairly common in the industry to see these trucks lift their front axles off the ground when picking a large load. This analysis will define the hook load at which the front end will come off the ground and whether or not it can be done safely. In crane design generally, the limiting factor is stability, not structural strength; the crane’s capacity is generally set at the maximum load for which the crane can remain stable. To increase this capacity, cranes deploy outriggers and counter weights that help it remain stable. Can the same theories be applied to bed trucks in order to increase that capacity while remaining stable?

Load and Stability Analysis #2

The second load and stability analysis will be looking at how stable the truck and pole are perpendicular to the frame rail. This analysis will answer how much load can be applied to the side of the truck before it becomes unsafe. This will translate into the real world as to how far off vertical can the boom be loaded or how heavy of an object can be drug sideways. There is also a structural element to this analysis because when used in this way, the pole will be experiencing forces that it wasn’t necessarily designed to see.

Pick and Carry Capacity:

The pick and carry capacity will combine the two load stability analysis as well as a dynamic analysis. This will model how the loading changes on the pole when a driver picks up a heavy load and tries to drive around with it. This is a fairly complex analysis as soon as you introduce a swinging load caused by uneven driving conditions. This will also address minimum tire pressure and maximum slopes that unit can operate on.

Variable Pole Angle Chart:

Develop a load chart and a safety procedure that will address how much can safely be picked with different angles of pole.

Tandem Lifts:

It is fairly common for pole trucks to pick and carry a load in tandem taking the load right off the ground. This section will review procedures for this and possibly looking and worst-case scenarios if the two trucks are not in sync as well as reviewing the maximum tandem lift capacity.

Customer Specified Lifts:

This section is reserved for any analysis required for a specific customer driven lift.

Image source: http://mcadadrillingfluids.com/blog1/wp-content/uploads/2012/03/ginpole-trucks-full3.jpg

Building a Program around the Engineering:

In order to fully leverage the engineering on a project like this we need to be able to apply what we find to as many gin pole trucks as efficiently as possible. This means that we need to develop a system to collect data from existing units, evaluate their worthiness to work and perform any repairs or modifications necessary. It will also require a network of shops and personnel to perform the actual work throughout western Canada.

A Crane Inspection platform would be a perfect launch point to address all the gin poles that are currently in operation but not certified. The program works as follows: Sparta starts by generating a set of inspection and test plans that need to be filled out in the field. These test plans will outline all the data that needs to be collected for engineering as well as the critical points that need to be inspected for workmanship, wear and quality. The major points of this inspection have already been outlined in the IADC guideline. Internally, Sparta generates calculators that can process the data collected in the field quickly and efficiently in order to evaluate the design. Next, several appropriate shops can be selected to get qualified to do the work.

Once up and running, the owners of the gin poles can take their unit to any of these qualified shops where the onsite inspection personnel will evaluate the worthiness of the unit. The shop will collect data using the templates and ship the data they collect to Sparta so the design can be evaluated. Any deficiencies can be resolved right at that shop. Once engineering and the onsite inspector are satisfied the unit is safe and ready for operation, Sparta will provide a certification to go with that truck.

Conclusion:

Gin poles are a piece of equipment that has largely fallen through the cracks as far as updating safety parameters and regulation in the oilfield. They are a large piece of equipment with capacities similar to that of some cranes but don’t use any outriggers, load charts or safety equipment that is now standard on cranes. In order to address this I believe a two-step approach is ideal. First, go through the engineering on a pole truck in a high level of detail to develop procedures and standards and minimum design requirement. Once complete, this design can be manufactured in any of the manufacturing shops qualified to do so.  Utilizing a Sparta developed program and the crane inspection platform develop a procedure and a network of shops capable of evaluating and certifying existing gin pole trucks. Output will ultimately include a more in-depth recommended practice that focuses on design and engineering that can be used in conjunction with the IADC guidelines.

Thank you for taking the time to read this proposal and I look forward to hearing your comments.