Plant engineers are saddled with an important task: outfitting their plants with the most reliable, high quality and cost-effective valves for their applications within their allotted budgets. But choosing the right valve is a complex process that has a major impact on plant operations as well as revenue.
If a valve fails in a process application, end users lose valuable time and money to replace or repair the valve. In some cases, entire areas of a plant may need to shut down for the fix, and unexpected downtime is costly. That’s why many plants choose valves based on history, performance, specification, quality and cost. When making purchasing decisions, plant engineers, maintenance and purchasing personnel must be able to evaluate available options for their facilities and consider both short- and long-term impact.
These decisions will only get harder given the growth of the industry. Forecasts by VMA and other groups predict that demand for industrial valves in the U.S. will increase significantly over the next half decade. This uptick means plant engineers will be even busier making major buying decisions.
The two most basic factors in the valve purchase-making process are functionality and price point. However, both internal and external factors often have an effect on and can muddy the waters and complicate decision making. Examples include:
The economy. Even when industries experience economic slow-down, plants must continue to operate at optimal levels with minimal downtime. To do so sometimes requires replacing aging infrastructure or completing major renovations despite the lagging economy.
Recently, the declining prices of crude oil have put the oil and gas industry under pressure. While consumers enjoy lower prices at the pump, U.S. oil companies are tightening purse strings and operating on smaller budgets to remain competitive. Despite this major economic factor, oil and gas plant engineers and maintenance personnel still must ensure their plants operate at maximum efficiency and adhere to safety and environmental standards, and they do so under pressure from tighter capital budgets.
Product selection. Plant engineers and maintenance personnel commonly work with valve manufacturer representatives and distributors that assist with proper selection of valves and actuators. Key factors include selecting the proper valve body and trim materials based on pressure, temperature and media. Many manufacturers offer customers and distributors a chemical resistance guide to aid in selecting the correct body and trim materials. Many of these chemical resistance guides provide a rating for standard valve materials used in common applications, ratings that also are often found in the manufacturer’s printed literature or website. This information allows customers to choose the best option for their particular applications. For instance, some chemicals work well with certain valve body materials, but only up to a specific temperature. In some cases, several valve body or seat materials may receive an acceptable rating, then customers might choose the lowest cost option based on product compatibility. In a nutshell, most applications may have several different material options so plants often determine the best solution for long-term needs. This is because specifying the right product is critical for long-term performance, and misapplied valve products may cause unexpected downtime.
Consider Costs and Cost of Ownership
The cost of a valve usually means the upfront cost to purchase and install the product. In the most basic of scenarios, a plant engineer might have a choice of two valves, both of which would perform the necessary duty, but with a disparity in pricing.
Cost of ownership, on the other hand, includes long-term and often hidden implications of a product choice. Evaluating cost of ownership requires plant personnel to look past product function and initial pricing. The factors they must consider could include:
Valve quality. Just like with any consumable good, valves built to last longer typically cost more upfront. For example, carbon steel is often less expensive initially than stainless steel. However, while both may perform the needed function, the carbon steel valves may have only a satisfactory chemical resistance rating. This could lead to regular maintenance and replacement costs since their lifespans are typically years shorter than their stainless-steel counterparts. By choosing the costlier option upfront, a plant will need less manpower to maintain the valve over time and can avoid repair and replacement costs.
Factors that increase the quality of a valve, and thus sometimes increase the cost, include:
Valve materials. Besides carbon and stainless steel, valves are made from many other materials such as, ductile iron, cast iron, bronze, plastics and specialty alloys. Each has a different cost point.
Valve technology. Valves are typically offered in two classifications: rotary (gate, globe) or quarter turn (butterfly, plug or ball valves). Each has unique characteristics, and in some cases, several different options are considered by plant engineers before they determine the best valve for the application.
Manufacturer testing. Valve manufacturers test their valves to meet certain specifications. Some manufacturers will meet a wide range of industry specifications while others may be limited to just a few. Manufacturers build their valves and provide detailed instructions and training on how to install, operate and maintain their products. The manufacturers who have invested in the design of their products and quality training to end users may require a premium to recuperate their investments.
Quality assurance. Some valve manufacturers have multiple plants all over the world producing valves. Customers rely on manufacturers to have consistent quality assurance programs in place globally to minimize or avoid receiving defective products from other areas.
Valve applications. Valves have limits for specific pressures and temperatures. Some new packing and seat designs allow for the same valve to be used in many applications while other designs are unique for specific applications. Valves with wider limits may cost more, but since they can be used in different scenarios, they can potentially cut customers’ storeroom carrying costs. One example is Teflon valves. Traditional Teflon can stand up to 400°F (204°C) of heat. However, newer valves that contain Teflon with glass fillers can withstand up to 500°F (260°C). This second type may be slightly more expensive, but they can be used for more applications, potentially reducing the need for multiple valves on the store room shelf.
Standardization. Standardization means committing to one reliable manufacturer for supplying valves plant-wide. This may be costlier upfront, but it also means fewer repair kits or duplicate products in storage. It also can mean better trained plant employees who have had the opportunity to become experts in operating and maintaining the products from their chosen manufacturer.
Repair or replacement costs. At some point, all valves need to be repaired or replaced. The cost to repair or replace a valve is part of the cost of ownership. The timeframe and frequency of such maintenance plays a major role in the longer-term cost. Plant engineers can educate themselves on the proper servicing of their selected valves and add that estimated cost to the upfront cost of the valve. They may determine that a higher-priced valve requires less maintenance and has longer life, ultimately costing less over the course of the expected lifespan.
Valve purchasing is not unlike the process consumers face any time they purchase a common household item. Consumers, like plant engineers, live within a budget, and that sometimes means making a purchase based on function and price. But when the research is done and factors such as quality, reliability, maintenance cost and expected lifespan are taken into account, a different picture of what constitutes the best choice often emerges. VM