Showing posts with label DHV. Show all posts
Showing posts with label DHV. Show all posts

Wednesday, July 6, 2016

Wellhead Valves Meet Special Application Challenges

Wellhead in oil and gas industry with equipment and valves
Numerous valves are employed at oil and gas production site
Industrial valves are manufactured in a huge array of configurations to accommodate the specialized needs of a broad range of industrial process applications. The oil and gas industry is but one segment of many throughout the industrial sphere that presents its own set of application specific criteria.

Oil and gas production, essentially pulling raw material from the earth, has unique valve performance challenges. Extreme pressure and abrasive or erosive material are common elements of oil and gas production at the wellhead. The valves also need to tolerate the range of outdoor temperatures at the production site. Safe and reliable operation throughout these and a range of other conditions are part of the design criteria for these valves. Here are some of the specific valve variants and configurations applied in the oil and gas industry at the production wellhead.
swing type check valve for oil and gas production wellhead or manifold
Swing Type Check Valve
Courtesy DHV Indutries
cutaway view of slab gate valve for oil wellhead use
Cutaway view of Slab Gate Valve
Courtesy DHV Industries

  • Slab Gate Valve - Provides metal to metal seal and employs parallel gate and seal with a preloaded spring to assure positive upstream and downstream seal. Full port design allows for pigging.
  • Expanding Gate Valve - A parallel expanding gate seals positively against both seats, which are protected from the flow medium in the open and closed positions.
  • Mud Gate Valve - Designed to provide positive closure under rigorous field conditions with abrasive media. 
  • External Sleeve Adjustable Choke Valve - Designed to regulate production well flow and downstream pressure. Different trim configurations provide appropriate levels of control.
  • Needle Adjustable Choke Valve - Utilizes different trim arrangement than external sleeve type to provide good flow management, abrasion resistance, erosion resistance, and reliable service over a long life with low maintenance requirements.
  • Check Valve - Check valves of various types are utilized throughout practically all fluid flow operations, essentially anywhere that fluid is supposed to flow in only one direction. Oil and gas production presents some special conditions of abrasion, erosion, and pressure that call for special accommodation in design and materials of construction.
There are other specialty valves employed at or near the wellhead, but the key take away here is that oil and gas production generally cannot be accommodated by general purpose valves. I have included a document below that provides additional data and engineering detail for the valves touched upon in this article. Share your oil and gas production challenges with a valve specialist. The combination of your process and production experience with their product expertise will produce effective solutions.


Friday, June 19, 2015

Industrial Control Valve Basics - An Introduction

Industrial process control valve
Globe Valve with Pneumatic Actuator
Courtesy Warren Controls
Valves, mechanical devices able to control flow or pressure in a process or system, are as ubiquitous as any industrial process control element. As essential components of piping systems conveying liquid, gas, vapor, or slurry, valves are a component with which almost every industrial process and control engineer will require more than entry level familiarity. They are the controlling element in almost any fluid handling system. What are some of the very basic knowledge points for specifying and selecting a control valve?

There are numerous types of valves available, including butterfly, ball, check, globe, gate, diaphragm, plug, and control valves as the most common. Particular valve types can be better suited to the medium being controlled, or have functional capabilities making them a better selection for your process application. Within each type there will be a wide range of options and features that allow for close tailoring of the complete valve assembly to match the application requirements.  Some valves can be self-operated, while others require manual operation. A pneumatic, hydraulic, or electric actuator can be employed on certain configurations to provide for remote control of the valve by a human operator or automatic controller.
General valve functions include:
  • Flow start or stop
  • Flow rate increase or reduction
  • Diversion of flow in another direction
  • Regulation of a flow or process pressure

Industrial process control valves are often classified according to their mechanical movement. Some common examples include:
  • Linear motion valves, in which the closure element moves in a straight (linear) direction to control the flow. Gate, globe, and diaphragm valves are in this category.
  • Rotary motion valves have a closure that follows an angular or circular path. Butterfly and ball valves are in this group.
  • Quarter turn valves, a subset of the rotary motion class, traverse from the open to closed state when the closure element (for example, the ball in a ball valve) is rotated through a quarter of a full turn. This type is best suited for operations calling for either fully open or closed regulation, with no need for control at points in between those two states.

Each industrial control valve application and installation will have its own set of very specific requirements. The goal of the specification and selection process should be to provide safe operation, low maintenance requirements, robust and accurate operation. A manufacturer's sales engineer can be a useful source for application and specification information and assistance.
Oil Pipeline Valve
Ball Valve Installed in Pipeline
Courtesy DHV