U.S. and Canadian Coast Guard, American Bureau of Shipping, and Lloyds Register accept the Flexible Reach Rod concept for marine use.
Flexible Reach Rod systems performance depends on four basic considerations:
1) Size and type of valve
2) Product which flows through valve
3) The length of the run
4) The amount of effort that one person is able to exert on a hand wheel
Southland Steel & Supply LLC
PO BOX 1011
Houma, LA 70361
Torque loads required to operate valves vary widely between different manufacturers. To specify a given operating torque for all valves of one size and type would not indicate with sufficient accuracy the actual torque to be considered when designing a flexible reach rod control system for a particular valve.
However, it is possible by assuming that a valve hand wheel is large enough for one man to operate, to base the design of a remote system on the size of the valve hand wheel and the “normal” effort which the average person is able to exert on a hand wheel rim. This information will follow in table #1 and is self-explanatory. One Man can apply a “normal” effort to the hand wheel of a valve provided the hand wheel is located lower than the persons head so that they can apply both hands, without difficulty, to the hand wheel rim. Under these conditions it has been found that his effort will vary from 35 lbs. Of pull per hand on a 4” hand wheel to 66 lbs. Of pull per hand on a 24” hand wheel.
It is an approved practice to support the flexible reach rod using various types of brackets every 36 to 48 inches. It is realized that this is not practical in every instance but it should be the installer’s objective at all times. However, it is important that the flexible reach rod be supported at both ends of each bend.
Formulas are available to allow the engineer to designate a particular flexible reach rod based on valve size, types, its working pressure and the distance from the operator to the valve. This information is available on request. However, the technical information furnished in this bulletin should be sufficient for normal decision making regarding which reach rod is necessary for a particular application.
Remember that the torsional deflection or the angular difference in twist is between input and output ends of a flexible reach rod system are directly proportional to its overall length. It is recommended that the total deflection caused by using a maximum input load be maintained at no greater than an accumulative 180° (degrees). (See Table #2). by using this as a guide, it will assist the engineer to correctly recommend the flexible reach rod to be used for a particular valve.
The flexible reach rod as assembled is lubricated, and under normal circumstances, should not require re-lubrication for up to three years. However, there are grease-fitting plugs in the lower and upper ferrules that can be removed and replaced with a zerk fitting. In cases of extreme temperature conditions, special lubricants are recommended that would ensure
Lubrication of the flexible reach rod is accomplished by first removing both grease fitting plugs and installing a zerk fitting at the upper station. Manually pump the lubricant into the reach rod until grease flows from bottom plug hole. Reinsert grease plug at both ends and test the system. It is advisable to rotate the core at the same time that pressure is applied. This will ensure uniform distribution of the lubricant throughout the entire system.
Flexible Reach Rod / Small Valve
Flexible Reach Rod / Medium Valve
Flexible Reach Rod / Large Valve
Minimum Operating Radius
Rigid Rod components can be assembled into a valve remote control design for manual or power drive operation where use is intermittent or slow speed, and it may be operated in either direction of rotation.
The following Rigid Rod Guide Selection Chart will be useful guides in the Design of a valve remote operator. The selection chart has been organized around four design factors, involving varying numbers of components, and tabulates the normal (one man operation) output torques obtainable with various handwheel and rigid rod diameters.
The Flexible reach rod must be supported every 3-4 feet. This is necessary to prevent curling and kinking when a high torque is applied and to ensure that the ferrules do not support all the weight of the reach rod.
Flexible Reach Rods are often used in instances where they are only operated after long intervals of time. It is recommended that the flexible reach rod system be operated at least once a month.
In many instances where valves have not been operated for long periods of time, foreign material may collect on the valve disc and it will require high than normal torque to operate the valve. Application of force greater than one man’s effort at the remote station can cause failure in the flexible shaft system or valve thus requiring repair or replacement of one or both.
It is recommended that periodic inspection covering the entire length of the flexible reach rod should be performed. This includes a visual inspection for damage to casing, ferrules or the adapter. Once again, common sense is the criteria for this product.
Flexible Reach Rods Offer a low-cost, simple solution to valve control. In applications such
as the offshore workboat industry where indication and certified materials may not be required, these flexible reach rods offer the ideal solution.
A hex adapter can be used to provide operation; the operator end of the assembly may be
connected by a simple lock nut arrangement. The output end of the assembly can be male or
female adapter, which can mate with the valve coupling shown in or manual. The reach rod
assembly is available in three different sizes.
To choose the assembly for your application, reference the design section of our manual, or
contact SRR sales staff for a complete recommendation or field survey. In situations where
replacement of existing Flexible Reach Rods are required, SRR economy Flexible Reach Rods are interchangeable with most other manufacturers’ products presently on the market.