Friday, November 17, 2017

Scotch Marine Boilers

cutaway view of two pass scotch marine boiler dryback configuration
Cutaway view of two-pass Scotch Marine Boiler
Image courtesy Williams & Davis Boilers
Boilers have a long history in the industrialization of the world. They were a primary source of motive power for many decades in the industrial revolution. Boilers continue to be an important source of both heat and motive power.

There is no shortage of lexicon in the boiler industry, with many legacy names for particular boiler designs. A Scotch Marine Boiler is a firetube boiler that was historically employed on ships. Firetube boilers channel the furnace combustion and resulting flue gases through an enclosure (for the furnace) and smaller diameter tubes. The shell of the boiler contains the water and steam, with the furnace and firetubes immersed within. Heat is transferred from the furnace and tubes into the water, producing hot water or pressurized steam as the unit design intends. Most of the heat from fuel combustion is passed to the water from the furnace chamber, with much of the remaining heat from the flue gases transferring from the firetubes. Once leaving the firetubes, the gases pass out of the boiler to a flue or chimney.

A dry-back boiler uses an enclosed chamber at the rear of the boiler to distribute the gases exiting the furnace section into the many firetubes. It is essentially just a box with the open entries to the firetubes and the open exit from the furnace penetrating its walls. The dry-back design facilitates access to the tubes for inspection and service.

There are other boiler configurations that serve to maximize various aspects of cost, service, and performance. Share your steam and hot water requirements with boiler and combustion specialists, leveraging your own knowledge and experience with their expertise to develop an effective solution.

Wednesday, November 8, 2017

Eccentric Rotary Plug Control Valve

eccentric rotary plug control valve
The MaxFlo 4 eccentric rotary plug control valve
Image courtesy of Flowserve Valtek

There is an extensive array of valves from which to select for a process control operation. Each candidate valve is targeted by its designers for a range of fluid applications, fortified with construction materials and design features specifically suited for meeting the challenges of that application range.

Flowserve, under their Valtek brand, developed a control valve that combines a number of useful design features. The MaxFlo 4 is an eccentric rotary plug valve intended for fluid control operations. The valve has some attractive design features.
  • There is no shaft extending through the flow path, leaving flow unobstructed when the valve is fully open (see the illustration in the document included below).
  • Valve trim provides tight bi-directional shutoff.
  • Metal or soft seat construction is available to accommodate a wide range of applications.
  • A variant provides flange to flange dimensions that allow the MaxFlo 4 to drop in as a replacement for standard size globe valves.
  • High Cv rating may enable use of a smaller valve, when compared to other designs.
  • Precise position control is delivered by the shaft form and plug mounting.
  • Double offset eccentric plug eliminates sliding of plug across sealing surfaces, reducing wear and required seal maintenance.
More detailed information is provided in the document provided below. There is a revealing cutaway illustration showing the mounting and movement path of the plug. Share your industrial process control valve requirements and challenges with a valve selection and automation specialist to get the best match of control valve to application.

Thursday, November 2, 2017

Lined Ball Valves

cutaway view of lined ball valve
Lining of ball valves extends their application to a range
of corrosive fluids.
Image courtesy Flowserve - Atomac
Lined valves of all types have an isolating layer of material that keeps the media from contacting the valve body, maybe even the valve trim itself. The purpose of the lining is generally to extend the useful life of the valve by eliminating the corrosive effect that may be imparted by media on the valve construction. Lined valves, with no exception I can think of, will have metal bodies. The lining can be any of a number of materials that will be selected based upon resistance to degradation by the process media under consideration.

Lined ball valves deliver the performance of conventional ball valves, coupled with the corrosion protection afforded by an appropriate lining material.

  • Low pressure loss
  • Quarter turn operation
  • Simple automation
  • Positive shutoff
  • Low to moderate operating torque
  • Compact

Options for the ball configuration are available to meet throttling or other requirements. Automation can be accomplished via a range of means. For more information, share your valve and automation challenges with application specialists and leverage your own knowledge and experience with their product application expertise.

Thursday, October 26, 2017

Expanded Product Offering at CTi Controltech

emergency tank pressure relief valve- weight loaded type
This weight loaded pressure relief valve is one of the many
products from Groth used for safe and efficient tank operations.
Image courtesy Groth Corporation
CTi Controltech has added Groth Corporation to its roster of valve and valve automation products. Groth is a well recognized manufacturer of an array of pressure relief and related products routinely used for tank operations and other processes.
  • Pressure/Vacuum Relief Valves
  • Pressure Relief Valves
  • Vacuum Relief Valves
  • Pilot Operated Valves
  • Flame and Detonation Arresters
  • Emergency Relief Valves
  • Waste Gas Burners
  • Pressure Regulators
Groth products have been protecting refineries, chemical processing plants and facilities with atmospheric fixed-roof storage tanks for more than 50 years. The new product line complements and expands CTi Controltech's ability to deliver full scale complete solutions to their customers.

A general product guide for the Groth products is included below. More detailed information, as well as product application expertise is available from CTi Controltech. Contact a product application specialist, leveraging your own knowledge and experience with their product application expertise to develop effective solutions to your industrial pressure relief challenges.

Tuesday, October 17, 2017

Rupture Discs - Designed to "Fail"

double rupture disc assembly with holders and gauge
Rupture discs can be combined in series for additional functions.
Image courtesy Continental Disc Corp.
A rupture disc, sometimes known as a pressure safety disc, burst disc or bursting disc, is a one time pressure relief device most often used to protect a vessel, pipe, or container from over pressurization. As opposed to pressure relief valves, rupture discs are designed to function only one time by providing an instantaneous response to an over-pressure condition, providing sufficient venting flow to disallow any further pressure increase.

These sacrificial parts are designed to burst when pressure within production equipment exceeds a certain threshold by breaking down, stopping the process to prevent or mitigate hazardous events. Rupture discs are critical instruments utilized so that companies can ensure process safety as set forth by the International Safety Standards (IEC 61508/61511).

The safety devices prove most effective when they fail according to pre-established specifications. Inferior rupture discs may cause unnecessary and expensive production shutdowns by bursting at the wrong pressure. Adequate quality testing and manufacturing expertise assures performance in accordance with ratings.

Rupture discs are commonly used in chemical, petrochemical, nuclear, aerospace, medical, railroad, pharmaceutical, food processing and gas & oil applications. They provide primary or backup protection. Very often rupture discs are used in tandem with safety relief valves, protecting them from the process media and extending the life of the relief valve.

For more on rupture discs call CTi Controltech at 800-288-7926 or visit their website.

Monday, October 9, 2017

Considerations When Applying Inline Spring-loaded Check Valves

spring loaded in-line check valve
Cutaway view of connector style spring loaded
in-line check valve.
Image courtesy Check-All Valve
1) Installation and Mounting

Inline, spring loaded check valves can be used in horizontal or vertical applications with proper spring selection. This is most evident in vertical flow down installations. The spring selected must be heavy enough to support the weight of the trim in addition to any column of liquid desired to be retained.

2) Elbow's, Tee's or other Flow Distorting Device's
Inline, spring loaded check valves are best suited for use with fully developed flow. Although there are many factors affecting the achievement of fully developed flow (such as media, pipe roughness, and velocity) usually 10 pipe diameters of straight pipe immediately upstream of the valve is sufficient. This is particularly important after flow distorting devices such as elbows, tees, centrifugal pumps, etc.

3) Valve Material Selection
There are many factors that influence the resistance of materials to corrosion, such as temperature, concentration, aeration, contaminants, and media interaction/reaction. Special attention must be paid to the process media and the atmosphere where inline check valves are applied. It is always recommended that an experienced application tech be consulted before installation.

4) Seat Material Selection
Several seat material options are available for inline, spring loaded check valves. An allowable leakage rate associated with the “metal-to-metal” as well as the PTFE o-ring seat, is 190 cc/min per inch of line size, when tested with air at 80 PSI. Resilient o-ring seats can provide a “bubble tight” shut-off (no visible leakage allowed at 80 PSI air).

5) Sizing and Spring Selection
It is very important to size check valves properly for optimum valve operation and service life. Sizing accuracy requires the valve be fully open, which occurs when the pressure drop across the valve reaches or exceeds three times the spring cracking pressure. Again, it is recommended that an experienced application tech be consulted for help with sizing.

6) Shock-Load Applications
Inline, spring loaded check valves are not designed for use in a shock-load environment, such as the discharge of a reciprocating air compressor. These types of applications produce excessive impact stresses which can adversely affect valve performance.

7) Fluid Quality
Inline, spring loaded check valves are best suited for clean liquids or gasses. Debris such as sand or fibers can prevent the valve from sealing properly or it can erode internal components or otherwise adversely affect valve travel. Any particles need to be filtered out before entering the valve.

Share your fluid control challenges with product application specialists, leveraging your own process knowledge and experience with their product application expertise to develop effective solutions.

CTi Controltech Adds New Line of Industrial Check Valves

poppet spring loaded piston check valve with flanged connections
Cutaway view of spring loaded check valve
with flange connections.
Image courtesy Check-All Valve
Effective September 1, 2017 CTi Controltech is proud to announce that it is the exclusive Check-All Valve representative in Northern California and Nevada (excluding Clarke County).

Check-All manufactures in-line spring-loaded, piston-type check valves. All valves are available with metal to metal or soft seats. Sizes range from 1/8” NPT to 20 inch, and are available with a broad assortment of connections. Pressure ratings are available from full vacuum to 10,000 psi. Special materials available are Titanium, Alloy C-276, alloy 20 and many others. Fluoropolymer (FEP) encapsulated springs are available for special corrosion applications. Check-All is an outstanding source for all check valve, vacuum breaker, and low pressure relief applications.

Share your fluid control requirements with the fluid process experts at CTi Controltech, leveraging your own process knowledge and experience with their product application expertise.