- Published on Tuesday, 26 May 2015 16:16
- Written by Chris O'Brien
The performance of valves and other final elements have a significant impact on the operations and safety performance of a process plant. Establishing effective programs based on realistic performance expectations is necessary to balance both cost and risk. Cost drivers include equipment and maintenance costs while risk can come from health and safety concerns as well as equipment availability. Gathering trusted information that can help inform decisions related to these factors can prove challenging.
To create a holistic view of field failure information, several key things need to be examined. These include collecting failure data, the functional failure modes of the equipment in question, available field studies, and finally, application stress considerations. We begin by looking at the most common ways of collecting field data.
- Published on Sunday, 10 May 2015 11:53
- Written by Peter Cleaveland
From time to time, we will re-post particularly well-received articles that have previously run on VALVEMagazine.com so that those who might have missed them will be able to catch up on the best of the best. This article, on the 'True Meaning of Double Block and Bleed' initially ran on June 1, 2010.
It’s time to do maintenance on a section of process. You don't want to shut down the entire facility, so you decide to block off and depressurize just the section you're working on. Just upstream is a double block and bleed valve—a trunnion-mounted ball valve with self-relieving seals and a bleed valve to vent the cavity. You close the ball valve and open the bleeder. Now you can de-pressurize the line downstream and open it up to work on it.
- Published on Monday, 27 April 2015 11:25
- Written by David Matherly
It is well known that effective planning can save time and curtail expenses when production and utility plant areas prepare for upcoming maintenance turnarounds, outages, and shut-downs. Such planning is also a key component to effective management of both the internal maintenance employees and externally contracted technicians that perform the work. Since manpower resources make up a large portion of the total expenses associated with any outage, organizing those resources is as critical as organizing the process itself.
In many cases the outage is part of an existing plant preventive maintenance (PM) program: critical valves within the plant’s valve population have already been identified or repairs have already been scheduled. That PM program may depend on use of an existing computerized maintenance management system (CMMS), which can help when scheduling work to be performed and when reconciling a list of poorly performing valves already identified.
- Published on Monday, 20 April 2015 10:05
- Written by David Escobar
Industrial oxygen is used for many purposes: in a basic oxygen furnace for making steel, water pollution countermeasures, including sewage treatment, habitability and superfund site rehabilitation, and chemical processes such as production of vinyl chloride, nitric acid, epoxyethane and hydrogen peroxide. It is also used for medical treatment, life support in harsh environments and industrial gasses for welding and other processes.
The production of oxygen has risen from approximatey 470 billion cubic feet in 1991 to over 1.5 trillion cubic feet in the U.S. and more than 4 trillion cubic feet globally in 2014.
- Published on Tuesday, 14 April 2015 10:05
- Written by Elaine Thomas
Castings made from many different ferrous alloys are produced for many industries, including valves. This article provides a quick review of phase transformations and the basics of heat treatment. Carbon, alloy and martensitic steels are typically used in valves and four important factors are addressed:
- Ensuring the casting and/or weld is at temperature
- The importance of time at temperature during different cycles
- Lag time between oven temperature casting surface vs. centerline of thick section temperature
- The need to avoid temper embrittlement