by Tim Dorr

Different types of Ball Valves

Ball valve is a ball that is literally placed in a passageway through which there is a flow of the fluid. You would find that there is a hole in the ball where the ball opens as well as closes. There are some ball valves that permit only 90 degree rotation while there are others which can rotate 360 degrees as well. But you need to understand that it is necessary to have 90 degree rotation in order to close or open a ball valve. There is the handle that indicates the position of the valve ball. The valve is opened when the handle is found to be lying along the axis of the valve. There are also multiport ball valves that you can find in the market. When you observe the position of the groove you would be able to get to know the flow path through the ball. There is a ball inside the valve that has actually a hole at the middle. Liquid is flowed very easily when the hole is aligned with both valves.

Three way valve

When it comes to the basic ball valve it has a two-way valve. It has a single as well as straight passageway bored that is through the ball and makes two openings one in the inlet and the other at the outlet. You can also find a three-way valve when the third hole is partially holed through the ball. The valves control the throttle in a car. If you wish that the flow needs to be shut off completely, then ball valve works best in this situation. If you thought that ball valves would develop problems after using it for long period of time, then you are wrong as it would still work perfectly when you need again and again.

Different types of ball valve

Now coming to the different types of ball valve, there are three different types. There is a full port ball valve that offers no flow restrictions. It means that the fluid can flow freely through the ball valve when it is open. Then there is a standard port ball valve that does not have an oversized ball. So you can find that the hole is one size smaller than the passageway. The third type of ball valve is a reduced port ball valve that has even a smaller hole. It helps in the flow restriction when the liquid passes through the valve.

So, the ball valves give a lot of advantages to different industries.

by The U.S. National Archives

Pipe Flange Joint Poses Safety Concerns

A fuel gas pipeline in a pipe trench went under a road bridge inside a factory.  A flange joint, fitted with a compressed asbestos fiber (caf) gasket, was located only 2.5 m from the roadway.

According to the area classification code used by the company there was a Division 2 area for a radius of 3 m around a caf joint and road vehicles should not be allowed unrestricted access to Division 2 areas. The factory wanted to open the bridge to unrestricted traffic.

Use secondary containment with a sensor
My recommendation is to leave the gasket alone for the reasons mentioned by the operations department. I would add a jacket around the flange and a sensor to detect if there is any leakage. The jacket would provide a small amount of secondary containment but would also concentrate any vapors so that the leak can be detected more readily. The signal should be transmitted to the control room and to a traffic light located at the bridge that signaled if travel on the bridge was safe or not. Since the flange has not leaked to date is a good reason to leave it alone but it does not insure that a leak won’t develop in the future.

Properly dispose of the CAF gasket
The gasket may not develop a leak, but why play the odds?  SAFETY FIRST!  Replace the asbestos gasket with the spiral wound gasket. If the binding material is intact (not friable) remove it, clean and inspect flange surfaces, and dispose of the asbestos gasket according to regulations. If the gasket is friable it may be required to glove bag during removal by a supervised asbestos worker. Replace the studs and nuts with ferilium.  Then do a wire wrap with injector cap nuts and valves attached. Inject sealant through the valves into the space between the wire wrap and the gasket. This will insure the flanges integrity and prevent a major spill in the off chance the gasket should fail. If the area is able to trap the gas in the event of a leak, a lower explosive limit (LEL) gas monitor should be installed with a warning signal if area gets above the LEL. This may seem a bit extreme, however all data are not available and more measures may be needed.

Rather than replacing the gasket, use one of the proprietary “gasket bands” that several vendors make.  Some have the option with a grease zert to fill the flange gap with grease or other thixotropic material that would be pushed out under pressure.  After applying this, a six-month visual inspection would tell if there was leakage from the pipe because the grease would be pushed out from under the flange seal.  Provided the safety department, plant operators, and engineering personnel are all happy with the flange the classification of the area could be changed. The gasket replacement could then be deferred until a future “opportunity.”

If the flange is under the bridge and it is a confined space, gas testing may also be required prior to entering under the roadway bridge; the safety department should be able to make this rule clear.

Chuck Stewart, sr. process engineer
BP America, Houston, TX

Which is the safest route?
We can shift the flange joint away from the road bridge, remove the existing flange joint, and make it a welded joint. This will require hot work to be done. But this is a one time job and it is the permanent solution. By doing this we will obey the codes and safety.

www.DeltaMechanical.com is the largest non-franchised, residential plumbing vendor in the United States. There are seven operational offices and ten satellite offices with business privileges in thirty five states. We have over six hundred service vehicles on the road today and have pioneered a flat-rate pricing system for residential and commercial repipes that has now become the industry standard. Repipes of faulty polybutylene, KITEC, copper, and galvanized piping in both residential and commercial structures are our specialties.

by Trishhhh

Stainless Steel Pipe,stainless Steel Seamless Pipe

My company couldn’t see all the fuss. We had been hired by Bechtel as a subcontractor for the ill-fated Goro project to refine nickel ore in New Caledonia. Bechtel wanted us to match its pipe specifications. To us, this was just another symptom of a bloated project. We used to joke that Bechtel had two engineers for toilets: one for the men’s room and one for the women’s room. Looking back, Bechtel’s approach made sense: get the Stainless steel pipe specifications right or live with a project fraught with headaches — never mind other minor issues, i.e., safety, reliability and profitability.

The first decision in establishing a pipe standard is choosing whether it will be based on function or condition. A function-based specification would be something such as a sewer pipe or vent duct. A condition-based specification would discriminate between sewer pipe for corrosive versus sanitary service. Usually, a condition-based specification is best.

Collecting information is the next step. Pipe specifications often are presented in tables kept in massive volumes. What’s missing is supporting information explaining the basis for decisions like the choice of type 316 stainless steel over type 304L, or selection of Inconel 601 instead of Inconel 600. This omission in company records almost justifies the reluctance I’ve witnessed to challenge pipe specifications.

Once information is collected, you should budget time for careful analysis by a consultant. The idea is to look for discrepancies between the pipe specifications and for areas of improvement. For example, Trevor Kletz, in his book “Process Plants: A Handbook for Inherently Safer Design,” suggests eplacing fiber gaskets with spiral-wound gaskets because their leak rate is lower.

With the analysis complete, it’s time for a meeting. Bring together maintenance staff, project engineers, vendors and contractors to pencil in the details of the new pipe specifications. Leave detailed discussion of any contentious points to follow-up meetings. Rely on empirical data!

Sadly, plants seldom use one important source of empirical data — the corrosion coupon, which is a welded strip of metal designed to be inserted into a process. Instead, they allow analysis of the effects of corrosion on parent metal and welds. Coupons, which also can be used for gasket materials in some applications, provide real data well beyond those found in textbooks and from laboratory analysis, which seems artificial by comparison. The downside is exposure time; material evaluation takes months. But, believe me, it’s worth it.

Consider what happened on another project. We had to handle a feed stream of aluminum chloride added to a stream containing wet chlorine gas and vaporized titanium tetrachloride. A world-renowned valve material expert claimed that zirconium oxide would survive our process. Being prudent, I suggested coupons but was overruled because of time constraints. The expert was dead-wrong! What we saw was quickly dubbed “the jawbreaker effect” by our operators. Over about six weeks, the balls in our ball valves shrunk, flaking away from thermal shock. Coupons would have saved us more than million a/year in downtime during the next few years and justified a ball made of a more expensive ceramic.

With all basic facts now in hand, it’s time to schedule follow-up meetings to review the draft pipe specifications. The best format for these specifications consists of a single page summary followed by details, exceptions and references. The details should include gaskets, valves, fasteners (e.g., bolts), special fittings, construction aspects such as weld inspection and paint preparation, etc. If possible, review the specifications with your mechanics. They may want to pass on their wisdom on construction details.

Exceptions may exist, and where they do, they must be clarified and documented. Sometimes exceptions arise because a vendor can’t change a valve specification and an acceptable alternative hasn’t been found yet. In one company, we ordered a PTFE-lined plug valve and modified it to fit an actuator.

Keep the summary table relatively simple. It should include pressure rating; application, i.e., for which chemicals; connections, e.g., threaded or socket-welded; and material of construction. It’s best to isolate the summary table so that it’s compact and usable by those in the field.

References should include the ANSI number and the old pipe specification number it replaced if there is one. Clearly state temperature limits; separately cite test pressures for ambient pressure tests. If you must note vendor information, also try to include acceptable alternatives. Keep your options open with vendors. Saving a little money now on a sole-source contract often isn’t worth the headache later of finding a replacement when a part fails to meet quality standards.

An often-overlooked item is the cross-comparison table, which matches the new specifications against the old ones. This table is crucial for working with old vendors and old inventories.

Stainless steel seamless pipe specifications are one of the keys to safe plant operation. By not keeping them current or allowing them to become confusing or hard to use, you may encourage deviation from good engineering practices. Make specifications simple and easy to follow.

Related Piping Vendor Articles

In general, valves, cylinders and pumps have female threaded bosses for the fluid connection, and hoses have female ends with captive nuts. A male-male fitting is chosen to connect the two. Many standardized systems are in use.

Fittings serve several purposes:

-To bridge different standards; O-ring boss to JIC (hydraulic), or pipe threads to face seal, for example.
-To allow proper orientation of components, a 90°, 45°, straight, or swivel fitting is chosen as needed. They are designed to be positioned in the correct orientation and then tightened.
-To incorporate bulkhead hardware.
-A quick disconnect fitting may be added to a machine without modification of hoses or valves

A typical piece of heavy equipment may have thousands of sealed connection points and several different types:

-Pipe fittings, the fitting is screwed in until tight, difficult to orient an angled fitting correctly without over or under tightening.
-O-ring boss, the fitting is screwed into a boss and orientated as needed, an additional nut tightens the fitting, washer and o-ring in place.
-Flare seal, a metal to metal compression seal with a cone and flare mating.
-Face seal, metal flanges with a groove and o-ring are fastened together.
-Beam seal, a costly metal to metal seal used primarily in aircraft.
-Swaged seals, tubes are connected with fittings that are swaged permanently in place. Primarily used in aircraft.

Elastomeric seals (O-ring boss and face seal) are the most common types of seals in heavy equipment and are capable of reliably sealing 6000+ psi (40+ MPa) of fluid pressure.

Hydraulic hose is graded by pressure, temperature, and fluid compatibility. Hoses are used when pipes or tubes can not be used, usually to provide flexibility for machine operation or maintenance. The hose is built up with rubber and steel layers. A rubber interior is surrounded by multiple layers of woven wire and rubber. The exterior is designed for abrasion resistance. The bend radius of hydraulic hose is carefully designed into the machine, since hose failures can be deadly, and violating the hose’s minimum bend radius will cause failure. Hydraulic hoses generally have steel fittings swaged on the ends. The weakest part of the high pressure hose is the connection of the hose to the fitting. Another disadvantage of hoses is the shorter life of rubber which requires periodic replacement, usually at five to seven year intervals.

Hydraulic pipe is used in case standard hydraulic tubes are not available. Generally these are used for low pressure. They can be connected by threaded connections, but usually by welds. Because of the larger diameters the pipe can usually be inspected internally after welding. Black pipe is non-galvanized and suitable for welding.

Hydraulic tubes are seamless steel precision pipes, specially manufactured for hydraulics. The tubes have standard sizes for different pressure ranges, with standard diameters up to 100 mm. The tubes are supplied by manufacturers in lengths of 6 m, cleaned, oiled and plugged. The tubes are interconnected by different types of flanges (especially for the larger sizes and pressures), welding cones/nipples (with o-ring seal), several types of flare connection and by cut-rings. In larger sizes, hydraulic pipes are used. Direct joining of tubes by welding is not acceptable since the interior cannot be inspected.

Filters are an important part of hydraulic systems. Metal particles are continually produced by mechanical components and need to be removed along with other contaminants.

Filters may be positioned in many locations. The filter may be located between the reservoir and the pump intake. Blockage of the filter will cause cavitation and possibly failure of the pump. Sometimes the filter is located between the pump and the control
valves. This arrangement is more expensive, since the filter housing is pressurized, but eliminates cavitation problems and protects the control valve from pump failures. The third common filter location is just before the return line enters the reservoir. This location is relatively insensitive to blockage and does not require a pressurized housing, but contaminants that enter the reservoir from external sources are not filtered until passing through the system at least once.

Also known as tractor fluid, hydraulic fluid is the life of the hydraulic circuit. It is usually petroleum oil with various additives. Some hydraulic machines require fire resistant fluids, depending on their applications.

In addition to transferring energy, hydraulic fluid needs to lubricate components, suspend contaminants and metal filings for transport to the filter, and to function well to several hundred degrees Fahrenheit or Celsius.

Hydraulic pumps supply fluid to the components in the system. Pressure in the system develops in reaction to the load. Hence, a pump rated for 5,000 psi is capable of maintaining flow against a load of 5,000 psi.

Pumps have a power density about ten times greater than an electric motor (by volume). They are powered by an electric motor or an engine, connected through gears, belts, or a flexible elastomeric coupling to reduce vibration.

Common types of hydraulic pumps to hydraulic machinery applications are;

-Gear pump: cheap, durable, simple. Less efficient, because they are constant displacement, and mainly suitable for pressures below 20 MPa (3000 psi).
-Vane pump: cheap and simple, reliable (especially in g-rotor form). Good for higher-flow low-pressure output.
-Axial piston pump: many designed with a variable displacement mechanism, to vary output flow for automatic control of pressure. There are various axial piston pump designs, including swashplate (sometimes referred to as a valveplate pump) and checkball (sometimes referred to as a wobble plate pump). The most common is the swashplate pump. A variable-angle swash plate causes the pistons to reciprocate.
-Radial piston pump A pump that is normally used for very high pressure at small flows.

Piston pumps are more expensive than gear or vane pumps, but provide longer life operating at higher pressure, with difficult fluids and longer continuous duty cycles. Piston pumps make up one half of a hydrostatic transmission.