Consulting Services

Consulting Services Brochure The basis of our business is solving bolting problems. We specialise in bolting related matters and provide independent and impartial advice. By having extensively researched the subject and by keeping up to date with the published literature, we can offer state of the art solutions to your fastener and bolting problems. Our consultancy service includes:

Resolution of product service and in-field problems that have fastener related issues.

Fastener Failure Analysis (fatigue, tensile fracture, thread stripping, galling, insufficient preload, creep, stress relaxation, self-loosening).

Determination of forces acting on the fasteners within a joint and the .

Torque Tightening Analysis and torque auditing procedures.

Flange/gasket leakage problems and issues associated with the tightening of large joints.

Fastener size and strength requirement determination.

Problems in which fastener self-loosening is occurring.

Fastener design problems in which fatigue is a cause of concern.

Our approach is analytically based and whenever it is feasible we quantify the issues we discuss.

We have an extensive library of technical resources (probably the best in the business) that includes technical reports, articles, research studies and standards on bolting related topics, all of which is indexed.

Titles in our Library 

Compressive Stress Distribution We pride ourselves on communicating the resulting analysis and opinions in a concise and easy to understand manner. If you have a problem that you think that we may be able to assist you with, why not contact us for a no fee, initial consultation.

Problems can often be solved more effectively with assistance from an outside organisation offering a fresh and unbiased view combined with extensive experience of solving similar problems across a range of industries. Examples of the problems that we have previously investigated are briefly outlined below:

A structural integrity assessment of the bolting on a sprocket of a military vehicle. In-service reports of a loosening problem on the bolting were investigated and an explanation was provided, based upon a joint analysis, of the root cause of the problem. Based upon the analysis, proposals were made on how the loosening could be resolved.

Fatigue failures had been experienced on fasteners that secure vibrator motor drives in an asphalt mixing plant. The vibrator motors have balance weights attached to them that generate motion to drive a screen that segregates stones. The vibration is extreme and the fasteners have to hold the motors in place. Based upon a joint analysis the root cause of the fatigue problem was established and proposals submitted so that the issue could be resolved.

An investigation was completed on the effect of the tapping drill diameter and thread engagement length on machine tools. There are manufacturing advantages in having a large tapping hole in that the holes can be tapped faster with a reduced risk of tap breakage. For the particular application the tapping hole diameter was optimised so that the required thread stripping strength was achieved.

An investigation was completed on the root cause of a loosening problem on bolts securing rail track to a bridge structure. Based upon reference to published research and joint calculations that were completed, proposals were submitted on how the problem could be resolved.

M24 Bolt Failure

A structural integrity assessment was completed on a high volume medical trolley in which bolt fatigue failures sporadically occurred. The work involved the completion of a joint analysis coupled with torque-tension tests to establish the appropriate tightening torque and investigate joint relaxation (which was found to be a significant contributory factor). Proposals were made in ways the joint could be improved to be more fatigue and relaxation resistant.

Thread stripping strength calculations on tapped holes in an axle to investigate occasional problems experienced in this regard. Recommendations were made on how the problem could be resolved.

A structural integrity assessment of bolting on a magnetic relay. Preload loss of the fixing screws it was found was caused by differing thermal expansion rates of the materials comprising the joint and embedding loss within the laminations. A series of proposals were made to resolve the problem that included optimising the tightening torque and changes to the design so that it was more resilient to the forces that it was experiencing.

A manufacturing process specification was completed for a major aerospace manufacturer on the installation and inspection of fasteners. The work included written details of how fasteners should be installed, tightened and inspected. This included torque recommendations and how residual torque measurements should be completed.

Fatigue failure of flanged bolt

A structural integrity assessment was completed on a joint that secured a winch to a ship’s deck. Forces acting on the individual bolts were computed and a detailed joint analysis completed. Recommendations as to the number, size and strength of bolts that were needed were provided together with details of how they should be tightened.

A root cause investigation was completed on why securing bolts were occasionally failing on the brake disk of a locomotive. An assessment was completed of previous investigations and potential flaws in the previous analyses. Based on an analysis recommendations were made on how the failures could be eliminated.

A structural assessment was completed on a cable protector assembly. A number of concerns with the design were revealed that included a thread stripping issue. Recommendations were made on how design changes could be implemented that would structurally improve the product.

Wheel Stud Failure

A joint analysis was completed on a piston rod of a hydraulic cylinder. The purpose of the calculations was to check if the thread size used was capable of sustaining the applied forces and providing an adequate fatigue life. Based upon the calculations, it was determined that the fatigue would occur in the thread prior to the required life being achieved. Design changes were proposed to allow an improvement in fatigue life to be achieved.

An investigation was completed into the cause of the detachment of the hook from a 25 tonne crane. The root cause of the incident was established and recommendations made on how the occurrence could be prevented in the future.

An investigation was completed into the cause of nuts self-loosening in the roofing structure of a building. The root cause was investigated and solutions proposed.

A structural integrity assessment was completed on the key joints comprising a piling hammer. The joints sustain extreme shock loading. Proposals were made that included the fastener design that was more resilient to shock loading together with tightening procedures and maintenance recommendations.

An investigation into the cause of a joint failure of a control arm to the hub and sub frame of a passenger car. A joint analysis and examination of the failed parts allowed the root cause to be established.

An investigation into why preload loss was occurring on used to secure brackets to the primary lining bolts in the tunnel. The investigation involved inspection and torque audit measurements completed on the bolts installed in the tunnel. Laboratory tests were also completed to determine the torque-tension relationship and longer term tests to investigate the relaxation being experienced.

Torque Tightening

A stud that secures a punch head to the punch on an aluminium can extrusion machine was occasionally failing resulting in damage to parts and a loss of production. An investigation into the problem was completed to establish the probable cause of the failures and potential solutions.

Problems were being experienced with the seizure of nuts onto bolts having a polyamide coating on the thread. The seizures appeared to be from galling but a detailed examination and measurements revealed that the root cause was a thread tolerance problem.

An investigation was completed into the structural integrity of M20 bolts used in a critical joint on a train. The work involved laboratory test measurements to establish the torque-tension relationship for the bolts and an assessment of the required torque required to meet service loadings.

An investigation was completed into the causes of loose nuts on the wheels of buses. Based upon this the likely causes were established and recommendations made on how the problem could be eradicated.

An analysis was completed of the failure of a M140 bolt due to thread stripping. The investigation involved the determination of the theoretical thread stripping force and recommendations on how the design could be improved to prevent further failures.

An investigation was completed to determine the torque value for a M64 studbolt. Based upon an investigation a bolt had failed on an installation by what is thought to be due to hydrogen embrittlement. The optimum torque value was established and recommendations made on how the scatter in the preload could be minimised.

Photo of a fatigue failure of a bolt

An investigation was completed into the cause of a bolt loosening problem on a turbocharger. The particular turbocharger application was subject to high levels of vibration and thermal cycling. Stress relaxation and embedding loss were factors in the problem. Based upon the investigation changes to the bolt material, specifying a tightening procedure and the introduction of other design changes were proposed to overcome the problem.

A large sleeve and capnut with a M100 x 2 thread experienced a stripping failure. Calculations were completed to determine theoretically the failure load. Recommendations were submitted on how the problem could be prevented from occurring in the future.

A review was completed into work that was proposed to prevent further instances of a leak on a large bolted flange at a nuclear power station. The proposals made involved how residual torque measurements should be completed to allow a more accurate preload assessment to be completed.

An investigation was completed into the causes of the loosening and failure of a bolted joint on a turbocharger. The root cause of the loosening was established and appropriate recommendations made on how the problem could be resolved.

If you think that we could possibly be of assistance to you in providing you with assistance with bolting analysis, please contact us.