Valve reconditioning can save time and money

Published: 25th September 2009 | Issue 2 Share article:

Like any other mechanical device, valves eventually need
repair or replacement. The frequency of repair and/or replacement will depend upon the severity of operating conditions, the design of the valve and the preventive maintenance that has been performed.
Valves are vital components in every process where fluids or gases are handled and their replacement when worn is not only costly but can lead to production losses if new valves of the type required are not immediately available.

Such arguments are gaining an increasing influence on process engineers to consider the economic benefits of valve reconditioning at a time when prices are fluctuating, quality from some sources questionable and the delivery delays for some classes of valve continue to grow. Valve users need look no further than cost savings and availabilityto justify a decision to hand over their valves to a specialist reconditioner. With typical savings averaging around 50% - considerably higher in many cases - and
delivery in terms of days or weeks rather than perhaps months, the advantages are obvious.

Conserving and recycling Wider benefits are now also emerging in the form of the valuable contribution which valve reconditioning makes to the national economy. Itprovides an efficient and economic means for conserving and recycling the costly and increasingly scarce materials ofwhich valves are made and, which is probably more important at the present time, for conserving the skilled labour content of the valve. Skilled labour is one of the most serious limiting factors in engineering, and the Sector Working Party of the National Economic Development Council on Pumps and Valves reported that unless ‘priority action’ is taken, a `severe shortage’ of skilled manpower would emerge in the industry. Extending the life of existing valves by reconditioning is clearly a way of overcoming the skilled manpower shortage in valve manufacture. Comid firmly believes that its specialist valve reconditioning activities benefit both the customer and the engineering economy as a whole. It applies this philosophy of cost saving and conservation through its Valve Reconditioning Service, which has developed over the past thirty or more years.
Valve reconditioning is a wellproven procedure under which customers’ valves are taken to the reconditioner’s works for refurbishing and testing and then returned to the customer. A similar service is offered by a number of UK companies, some of which are valve manufacturers. Comid has a different history however, and believe having concentrated all their resources in equipment and skills on the maintenance side of the business, they are able to offer a service which covers almost every type of valve from any manufacturer and which can be tailored to the individual customer needs.

Specification assurance
By whatever route valves are reclaimed, process engineers need assurances that the valves have been restored to a recognised standard. Valves which have
been returned to a plant after reconditioning must continue to perform the duty for which they were originally installed in that plant. This is the crux of the valve reconditioning argument. The system stands or falls by the quality of the product which leaves the reconditioner’s works; the only acceptable criterion is that every valve must be restored to a condition equivalent to the valve manufacturer’s specification. Only if this can be assured will the customer have confidence in the valve. Techniques for achieving this have now been established by reputable valve reconditioning concerns and include welding to make good worn areas, machining and lapping to restore the correct dimensions and surface finish and the repair or replacement of damaged components. By applying these techniques in accordance with the best engineering practice, under experienced supervision and with strict quality control, a valve is restored to an ‘as-new’ condition. It should be stressed that although the refurbishing techniques involved are widely used in general production engineering, they must be applied with the distinctive principles of maintenance engineering in mind. The
approach therefore, differs considerably from that of production engineering and underlines the special role of the valve reconditioner as an integral part of the
maintenance engineering sector. Techniques and practices designed to restore a valve to the manufacturer’s specification provide a powerfulargument for valve reconditioning. Nevertheless, something more is required if an engineer is to have complete confidence in the refurbished product that he is proposing to incorporate in a plant which may have a vital role in the efficient and safe control of a process.

Reconditioner’s warranty
Standards must not only be established but must be seen to have been attained by appropriate test procedures, which will form the basis of the reconditioner’s warranty, supported, if the customer so wishes, by a Test Certificate, signed by an independent qualified or designated Engineer. Comid have set up test facilities which meet these requirements. Their equipment includes hydraulic pressurised pumps, gas pressure testing equipment and regularly calibrated indicator gauges. These test facilities are located in a separate area of the works, so that testing can take place in a clean environment. Hydraulic and/or gas pressure tests can be applied up to 10,000 psig (690 bar). If necessary, they can be witnessed by independent quality assurance inspectors, appointed by the customer or his insurer.

Purpose-built facility
Though there may be, in some cases, advantages in having the work done in the customer’s own works, those at Comid Engineering point out that, in addition to the problems of providing the necessary stringent tests on site, there is a lack of portable machines suitable to carry out the often extensive remedial work required.


The experience of Comid Engineering also suggests that, contrary to what might have been expected, site reconditioning does not always save time. This is because of the time saved by carrying out the work on special equipment in the workshops which have been carefully tooled up for this class of work, compared with the ad hoc methods which must necessarily be employed on site, where no two locations are the same. It is all a question of the quality of organisation a valve reconditioner can offer. This is where the experience of a company whose management has a sound background in maintenance engineering really counts. Such a background is essential for handling the variety of work which comes forward. Such work can range from a single valve which needs emergency attention, to a long-term contract involving the reconditioning of all the valves in a large plant on a planned maintenance basis. The successful reconditioner must be aware of the requirements and problems of maintenance engineering, and be able to handle both types of business with equal customer satisfaction. Since almost all valves can be economically reconditioned, the potential market for this service in process engineering is enormous. It is generally thought that wedge gate valves in cast iron below 200mm and in steel below 100mm nominal bore, are seldom worth reclaiming because of the cost of restoration relative to the price of new valves, but that all others can be reconditioned, with no upward size limit. Comid recondition valves in many sectors of process engineering, from power stations, oil refineries and petrochemical plants to breweries and water undertakings. The company also has a purpose built annex solely for the overhaul, reconditioning and testing of safety relief valves. Despite the emergence of ‘low value’ valves from the Far East the scope for valve reconditioning indicates a healthy future for this cost saving and resource conserving activity.


Comid
In addition to Comid’s renowned valve repair and valve reconditioning service disciplines, they have evolved their new valve and actuator sales to include most types of valves and actuators from various manufacturers. They also provide a complete on-site service package, including in-situ safety relief valve testing, for company plant shutdowns or outages.


Comid Engineering Ltd
Tel. 0161 624 9592
www.comid.co.uk, Email. alex@comid.co.uk

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