/ / Frequently Asked Questions
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1. What is Valve Live Loading?
The term "live loading" means using a Belleville spring to maintain load on a seal. Many valves utilitze studs or bolts to exert load on to the gland follower, which applies stress to the packing. As the valve is operated, the seal material consolidates during each operation. High temperature and thermal cycling can accelerate this loss. As this occurs, preload is lost on the seal, and once the preload falls below a certain threshold, a leak will occur. Since the stretch in the stud is small, loss of preload and packing stress can occur quickly.
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2. What materials can be cryogenically deburred?
Flange live loading with Solon Flange Washers manufactured with precipitation-hardened stainless steel are ideal in cryogenic applications where cold temperature and corrosion are factors in process leaks and fugitive emissions.
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3. What is the torque calculation?
The widely accepted forumal for torque calculation is: T=K*F*D, where K = estimated nut factor, T = bolt torque, D = nominal bolt diameter
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4. How do I know what material or finish would be best for my product?
Things to consider when choosing material are bolt material, temperature, environment, application, cost, availability.
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5. Under what condition is the deflection maximum and why?
The maximum deflection should normally be calculated as follows: MAX Deflection = MAX Overall Heigh - MIN Thickness
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6. Why is loosening prevention important for a bolted connection?
Download our technical white paper, Why Bolts Work (and Why Some don't), which discusses the three main important points to remember when bolting and why it is important to understand why factors such as embedment relaxation, differential thermal expansion (DTE), elastic interactions, vibration loosening, bolt creep, and component yielding cause bolts to lose load and how to counteract these phenomena.
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7. How to prevent bolt fatigue failures?
Download our technical white paper, Using Belleville Springs to Prevent Bolt Fatigue Failures, to learn how changes to a bolt, such as stiffness, will influence the cyclical load on the fastener. This paper takes a closer look at the science behind the elements of preventing bolting malfunctions, and explains how using Solon Belleville Springs & Washers increases the elasticity of the bolting system and maintains bolt preload.
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8. Are Solon Flange Washers corrosion-resistant?
Solon Flange Washers are heat treated using a recipe that achieves RH1065 condition while imposing an additional layer of protection from the elements, and undergoes a cryogenic sub-zero transformation and aging treatment.
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9. Can you stack Solon Flange Washers on one side of the flange?
There are some cases where flange springs must be stacked on one side of the flange. This might be because a tensioner is being used to load the studs. It also may be difficult to access one side of the flange. In addition, there are some applications where the flange is not bolted through, such as a valve bonnet or if one of the flanges is tapped. In these cases, if the recommendation is to use two springs (or parallel spring sets) in series, we recommend that it is verified that the clearance hole in the flange is less than or equal to the clearance hole of the flange washer. If the clearance hole is larger, then the convex side of the washer nearest the flange could "extend" into the hold of the flange and alter the loading charactertistics. Since the clearance holes in standard flanges is almost always larger than the clearance ID of the Solon Flange Washers, we would minimally recommend that a flat washer with an ID equal to the ID of the Solon spring be used. The flat washer should be a hardened washer to prevent embedment. Another option would be to use a thrid flange washer (or parallel washer set) on this side of the flange. Using an odd number of springs in series will ensure that the convex side of the first spring can contact the flange. The added spring will always provide additional elasticity so joint performance will be improved over two springs.
10. When do I need to use a flat washer with a Belleville?
It is common to use flat washers under the springs. Some general recommendations regarding flat washers for flange live loading applications include: a. We recommend that the flat washer material be in the same "family" as the Belleville. In other words, if the Belleville is stainless steel, the flat washer should also be stainless steel. b. The OD of the flat washer should be larger than the OD of the Belleville. This will ensure that the OD of the spring contact point bears on the top surface of the flat washer. c. We recommend that the flat washer be a hardened material. This will reduce the likelihood that the Belleville would embed into the flat washer. d. We generally recommend that the flat washer be 1/3 the thickness of the Belleville (or greater) when the flat washer is fully supported by the joint.
11. Do I install my washers on the nut or bolt head side?
Installing Solon Belleville of Flange Washers on the nut or bolt head side does not make a difference from a performance standpoint. Solon recommends that the user install them on the side that is most convenient to access. If this is equal, then we would opt to install them on the opposite side from the element that will rotate during install to reduce rotational galling on the spring. In other words, if the user plans to turn the nut during install, we would install them on the bolt head side and vice-versa.
