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Procuring new fasteners is nice, but customers are also able to have their torque-based products, with torque-based problems, converted to tension-based load indicating solutions.
From wind energy to refineries, we have engineered solutions that really work. Here are just a few:
Wind Turbine Tower Flange Bolts:
Valley Forge was approached by a major wind turbine operator who had concerns over loss of bolt load on wind turbine tower flange connections. Each tower consisted of four sections connected using approximately 100 bolts per flange.
The solution bridge that bonds wind energy and refineries
Wind towers annual maintenance required retorquing the flange bolts. If during the initial retorque it is determined that loosening had occurred, additional retorques are required. In improperly tensions joints water ingress is a possibility between the flanges. Ambient wind farm temperatures could fall below freezing and therefore a concern was that water ingress in the flange could freeze, forcing elongation or possible yielding of the bolts.
Valley Forge proposed a tension-based investigation and solution: It looked feasible to convert the bolts to introduce our SPC4® tension monitoring features and couple them with our 720R UHF Remote Tension Monitoring meters.
A site visit and solution try-out confirmed that the data transmission could be achieved from ground zero to over 400 ft above. The data collection was instrumental in determining the root cause and ultimately the solution to prevent catastrophic flange joint failure.
It is common knowledge that fasteners are manufactured to stringent specifications for material, mechanical properties and dimensions, but it is imperative that the proper design clamp load be established and maintained to insure performance of the joint. This customer provided bolting from their inventory to be converted with SPC4® technology. By adding the additional load monitoring technology, now all design factors can be met.
Oil Refinery Reactor Outlet Valve:
Converting and upgrading to a load indicating fastener is often the result of the need to continuously monitor clamp load on an assembly. In petrochemical facilities and refineries nearly all applications center around fastened flange joints such as a valve connection, line blinding, reactor bolting or shell and tube heat exchangers.
The solution bridge that bonds wind energy and refineries
Valley Forge & Bolt was approached by a major Gulf Coast oil refinery who had concerns about loss of bolt load on a reactor outlet valve. Several assemblies in the immediate area suffered from a leak on startup, gasket seating difficulties and, in some instances, required a steam ring. The need to control discharge and fugitive emissions was paramount and so a decision was made to have the flange sealed perfectly.
The application is a 20-inch class 600 flange which contains 24 ASTM A193 B16 studs with Grade 7 nuts. During installation the customer used a hydraulic wrench and employed a legacy bolting pattern using lightly lubricated parts to reach a desired target preload of 65%. Upon start-up and inspection, it became apparent the gasket was improperly seated. Further attempts to align the gasket and fasten the studs to the proper load resulted in flange leaks.
With an operating temperature of more than 750°F, Valley Forge recommended a standoff style SPC® load indicating stud for this reactor block. The standoff design allows for the nut on the indicator end to be simply hand tightened against a crimped area. This maintains calibrated accuracy. The position of the nut that is torqued on the other end has no effect on calibration. If removed, the indicator end nut can easily be relocated back against the crimp after stud insertion into the flange.
Valley Forge engineered a load indicating all thread stud to work in the assembly, the plant turn- around group installed it during their next outage. Using the same hydraulic torque wrench to tighten the studs the installation crew observed that they could establish a correlation between the clamp load their hydraulic tightening tools were showing and the true percentage of proof load imparted on the fastener. They reached a consensus that the joint characteristics of the assembly prevented operators from seeing and achieving the desired preload and, as documented in other units, the easiest and most accurate method of reading bolt load to +/-5% is by using a load indicating SPC4® or Maxbolt® fastener. The gasketed assembly has been in service a little over four years and with zero Leaks.
We solve complex bolting solutions every day. Check out a more in-depth case study in which we supplied this industrial heat exchanger with Valley Forge SPC4® Load Indicating Fasteners and saved this company over $250,000 in repair and maintenance costs. For more information or to talk to one of our technical experts, visit vfbolts.com.
