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  Experienced Manufacturer of Pipe Supports since 1978
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  Webinar Archives > Field Services

Field Services Webinar (July 2009)

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Text Version of the Field Services Webinar

This presentation covers the basics of field service and some experience we have gathered over the years. The topics today are going to be on-site survey & inspection, installation & maintenance, and problem resolution. For those unfamiliar with us, we would like to share a brief background on our company. Piping Technology & Products, Inc., also known as PT&P, has been in business since 1975. PT&P and its wholly owned subsidiaries, US Bellows, Sweco Fab, Pipe Shields, and Anchor Darling, offer a wide range of engineered products and services for various industries and applications. Our product line is extensive, from spring supports, expansion joints, pre-insulated pipe supports, and miscellaneous fabrication to various engineering and technical services, PT&P has decades of experience providing products and services for all your engineering and construction needs.

We have achieved various certifications here at Piping Technology & Products. We have the ASME U-Stamp and R-Stamp for the SWECO division of our company. We are ASME NS certified in our Fronek Anchor/Darling, Enterprises division. We are also part of the Expansion Joint Manufacturers Association through our U.S. Bellows, Inc. division. Most recently we received the ISO 9001:2000 certification for the manufacture of hot and cold supports. We are a Minority Business Enterprise granted by the City of Houston, and additionally, we are a member of the Houston Minority Business Council.

Survey and inspection is used to determine any irregularities, damage, interference, and general condition of a piping system. If there is interference occurring or the components are in poor condition, then the piping system will not function correctly. The guidelines for on-site survey & inspection are to be performed during operations, shut-down, or during both. It is best to do it at both times in order to understand the situation while in both hot and cold conditions. This is especially important for power plants, where there are generally old hangers in place and customers want to know how they function in both shut-down and operating conditions. It is important to set up times for frequency of inspections, with hangers and scaffolding available. It is best to have a set schedule for inspection.

inspecting a constant spring support in the fieldVariable spring supports operate like a bathroom scale over a load range. They compress when a load is placed on them and relax when it is removed. They are called variables because they can support a wide load range. There are many different types of variable springs available, so we shall give a brief overview of them. The first type is known as type A. It is used when there is a long distance, over 20 feet (7 meters), between the structure and the pipe that needs to be supported. The type B and C supports are both welded to the structural steel and are only different by their attachments. The type B attachment is a single lug attachment, that provides for different lateral movement. The type C is a double lug attachment with a single weld point at the top. The type D and E sit on top of the structure and are excellent for distances less than 4 feet. The type F support sits under the pipe, and can be under a dummy leg or straight pipe. The type G support, or gang hanger, is mainly used for short distances in which a full hanger will not fit.

For inspecting variable springs, we have a step-by-step procedure, or checklist, that we prefer to follow. The first items we inspect are the beam and pipe attachments. If these are in good condition, we know that the pipe hanger will not fall and the pipe will remain in position. The next item we check is the hardware for bends, breaks, rust, and missing locknuts. Last, we check the condition of the spring-can housing. It is undesirable to see a lot of rust or the coil area packed tight, so it cannot move. On F-types, we prefer to look inside and make sure the load column is centered under the load and free from interference.


The next stage is how to read a load column to make sure it is set correctly. You should be able to read it at the bottom of the indicator that shows the load on the can. If your load is greater than +/- 10% of your set point, you need to investigate the cause.

variable spring canIt is necessary to know when to replace a spring can. Look for signs of excessive corrosion or fatigue, rust damage, and modifications to the operating conditions. If the can is older than 30 years, it will probably need to be replaced due to the loss of spring rate over time. If the spring doesnt need to be replaced, it may need adjusting. It should be adjusted after installation and plant startup, if there has been a modification in the piping system, or if the load has been altered. We have found travel stops left in spring cans before, thus making it a ridged rod hanger. For example, when a can has lost its tag and it becomes unclear where its current load should be resting. If this occurs, you are welcome to call us and we will be able to calculate where the spring should be resting at in the system and provide a new tag for the spring.

The next topic of discussion is constant effort supports or constants. These are used where there are large amounts of movement, usually greater than 2. They provide a single load throughout the deflection of the coil, which enables them to provide the same load no matter the compression of the coil. This is used on a pre-stressed part of the pipe system or anywhere where the pipe should effectively weigh zero.

We have three different types of hangers and supports for constants. The horizontal constant has the spring on the side and compresses in a horizontal manner. The vertical constant is where the spring compresses in a vertical manner. The only real difference in operation characteristic is the footprint that they occupy. If a lot of space is available horizontally, we recommend utilizing the horizontal constant, and the vertical constant is better if there is a lot of vertical space. An upthrust constant sits underneath the pipe and only operates in a vertical manner. They cannot take lateral movement.

For inspection and maintenance on constants, we follow the same basic checklist as we do for the variables. There is one key difference. When looking at the load indicator, it needs to be between the hot and cold set points or at the hot and cold set points. Since the constants only operate at one load, there is no hot and cold load to worry about. It becomes necessary to replace the constant when there are signs of excessive corrosion or fatigue, rust damage of the entire unit, modifications to operating conditions, or consideration of internal components. We can adjust the load on a constant if there are some minor changes to your piping system. The change has to be less than 10% in weight. Also, consider position and movement when making adjustments. After a fire at a local refinery, we were called in to inspect the cans. We checked the internal components of the cans and the name plate to confirm the can size and movement. Then we determined if it was still operating normally or if it should be replaced.

Restraint devices are hydraulic snubbers, mechanical snubbers, sway struts, and sway braces. The goal of these supports is to oppose shock movement, winds, hurricanes, or anything that would cause your system to move in an undesirable direction. They will guide and restrain the movement in order to prevent your pipe inspecting a hydraulic snubber in the fieldfrom being over stressed. Hydraulic snubbers are designed to allow thermal movement, but restrain impulsive or cyclic disturbances. They are good for earthquakes, wind, and continuous thrust due to safety valve blow-off or pipe rupture. Mechanical snubbers are designed to prevent shock forces. They limit the damaging motions by becoming a load carrying member, or locking in place. Sway struts are used to restrain movement in one direction while allowing movement in another direction. They are effective under compressive or tensile forces and allow for field adjustment. Sway braces are recommended to reduce high frequency movement. They guide or restrain the movement of the pipe resulting from thermal expansion while bracing the pipe line against sway. They can also be utilized for tension or compression. The inspection procedures that we use are similar to the previous inspections. We check the end brackets and attachment pins, for a tight snug fit. We mark the actual hot/cold deflections for snubbers, leaks for hydraulic snubbers, and lockups for mechanical snubbers. Once done, we record and document all the findings.

You may have to replace a sway strut or snubber under several conditions. If the hydraulic snubber is leaking or if the seals fail you need to replace them. If there is a lot of damage to the snubbers or some serious deflection they are not going to function correctly. Only the C-C dimension or available length can be adjusted. For example, we came across a hydraulic snubber that was suffering from leakage. This could prevent the snubber from locking up with lack of fluid. If you come across this problem, you can call us and we can tell you with what fluid you should use for replacement, or if the snubber itself needs to be replaced.

Next we are going to talk about some of the assembly components for our hardware. The first heavy component is a fabricated clevis and is used for single lug suspension and very heavy loads. The second component is a fabricated turnbuckle, and it is used for an adjustment greater than 6. The third is a forged weldless eyenut. The fourth is forged turnbuckle, and it is standard up to 1 . They only have about 3 of adjustment, so its important to get full thread engagements. The last is figure 70 clamps. The wider the clamp the heavier the load they can handle.

clevis hanger in the fieldThe first two light components are the adjustable rings and adjustable clevis. They are used when you dont have a lot of weight to carry and dont mind your pipe sliding within your pipe supports. The clevis has a pipe shield used to protect the pipe from the clevis. Next is the double bolt pipe clamp. They are used when you want the pipe support to move with the pipe. The last two components are the trapeze hanger and the job-fabricated pipe hanger. They are used when you have multiple pipes to support, you have pipes outside your structure, or when youre adding new pipes to a system and it will not fit in your current system.

For inspecting these components, we use the same process as before; except, we just take off the parts with the springs and housings. We check for damaged support steel, hanger clamps, bent hanger rods, hardware, etc. In order to get a good inspection, you may need to use binoculars, scaffolding, or man-lifts. For replacement criteria, you need to check for bent rods and damaged hardware. The main thing to consider is are my existing hangers strong enough to carry my pipe as it is? If you make any changes to your system, you need to make sure supports are strong enough. For example, bent rods over time will get worse and will eventually fail.

There are many different pipes shoes from the simple split T, to the multilayer pipe support. Every place needs pipe shoes, from the simple farm pipe to power plants. When inspecting pipe supports, check for the condition of the steel. Check for rust spots, bent plates, slide plates, and the condition of slide plates. An example is where a slide plate was pushed off its support. As the pipe expanded and contracted it slowly moved the shoe and wore the PTFE, 25% glass filled, down.

Slide plates offer a low coefficient of friction for sliding surfaces. We use several different slide plates: PTFE, 25% glass filled, Graphite, Bronzphite, a combination of bronze and graphite, and Marinite. It is very important that these plates are installed correctly, or its very easy to tell if they are not. When inspecting, you should look for corrosion, bonding, damage, welds, orientation, gaps, or missing parts. You will need to replace the plates when it has suffered excessive damage to its surface, disbanding of the sliding material, improper size, or its the wrong plate for the temperature.

We manufacture many different expansion joints like thick wall, refractory lined, gimbal, elbow, universal, and double expansion joints. It is important when you have expansion joints in your system that you have an inspection routine for them. These supports have anywhere between 5 to 20,000 life cycles; which could last anywhere from a few months to years. It is important to check the line anchors and guides around the expansion joint because of their affect on the expansion joint. When inspecting the expansion joint, you need to check for movement, signs of corrosion, conditions of threaded fasteners, flow direction and position, and removal of shipping bars. The main things to look at are the convulsions in the metal bellows, leaks in the fabric bellows, and find any deformation. We dont recommend trying to patch steel bellows or fabric bellows. It is best to replace them.


Installation & Maintenance:

For spring supports, the first thing you want to do is affix the structural attachments to the steel and make sure the welds are in good conditions and lined up. Next you attach your clamps and the rest of your hardware, while using your turnbuckles to compress the spring until it takes the load off your temporary supports. Once its supported, you can removal the travel stops, which should come out easily by hand.

For adjustment you can alter your spring cans. This can happen if you need a new name plate or had a change in the load. First you mark you existing position, then measure the distance to the new load. Turn the load column until the bottom of the load indicator matches the new load. This is usually cost effective if your support cans are high load items, above the 20,000 range. Otherwise it is probably cheaper to replace them. For maintenance, there isnt a lot you have to do. Visually inspect them routinely and make sure nothing gets in them like bird nests. If youre going to work on a pipeline thats supported by variables or constants, insure you have installed travel stops. First you set up your temporary supports and then install the travel stops. You want to make sure you lock your cans on either side of the pipe. If you do not and open up a flange, the spring will release its energy and make reinstalling the flange very difficult. Always keep track of your travel stops and use them.

For constants, you can recalibrate to a new load if there is a less than a 10% change in load. This is also more cost effective on the larger constants. For the smallerConstant spring in the field. constants, it may be cheaper to just buy new ones. We recommend that you dont try to recalibrate it yourself, consult with us or have us send a team out to do it for you. For installation of snubbers and sway braces, the most important thing is to determine the direction of movement and install it in the center. Also, for hydraulic and mechanical snubbers it is important to not get any well splatter on the movement of the pistons which would cause it to interfere with the movement. For sway struts and sway braces, it is important to confirm your C-C or overall length. If youre going to be working on a line with snubbers, struts or sway braces, the main thing you want to do is mark your deflection on the snubbers and brace the load point on the sway braces. If you dont take into account the direction of movement, when you put it back in place, you could damage your pipe when it does move.

You use the same procedures for rod hangers as you did for variables and constants. First, secure the hanger to the existing structure. Attach the connecting rod to the beam attachment and pipe clamp. Transfer the load by rotating the particular component. The shutdown/isolation procedure is also very similar. They key difference is that you do not have travel stops. The lines/equipment must have temporary support while the repairs are made. For pipe shoes, the main thing you want to make sure is if it has slide support. If so, then you need to take that into consideration when you center it. If you know your pipe is going to move 5 in a direction, you offset your support 5. When the pipe does slide it will still be resting on your structural steel.

For expansion joints, the most important thing is to be careful with the convolutions. Also, make sure you do not have to squeeze or stretch the bellow to fit. If this occurs, the stress will cause the lifespan of the bellow to be reduces. For maintenance, you just need to visually inspect it occasionally.

 

Problem resolution:
Here are a few examples of some situations we have encountered in the field that may be on benefit to you.  The first case involved failing of roller bearings on the upthurst constants in a power plant.  This was caused by the movement on the pipe being lateral to the installation of the constant.  This caused the load travel table to push up against the roller bearings, causing them to come apart.  To solve this, we re-fabricated the shaft with two washers on either side of the roller bearings.  This caused the plate to hit the washers, not the bearings, making it a lot stronger.  The best solution, which was not an option, would have been to rotate the constant 90°.  The second case is an emergency that happened at 5pm on a Friday when an expansion joint failed, in which we where contacted using our emergency line.  One of the line anchors broke, causing the expansion joint to split.  We redesigned the new expansion joint Friday night, and sent the drawings for approval.  We added stiffener bars to help add more strength and by Sunday the new expansion joint was fabricated and installed on Monday.  The final case is more of an explanation of our installation and maintenance procedures.  When installing a constant, look at the travel stop pin.  If you see a lot of daylight under it, this tells you that the pipe support is not putting enough compression on the line and the coil is not holding up the pipe.  To fix this, you rotate the turnbuckle clockwise; this causes the spring to compress taking more load of the pipe.  This causes the spring to compress and allows you to take the travel-stop out with your hand.  If you have a lot of daylight over the top half of your pin, which means your coil is compressed too much.  You need to reduce the pull that the can has on your pipe by rotating the turnbuckle counter-clockwise.

Inspection and maintenance is a vital function to keeping your facility up and running.  There are several sever consequences from not inspecting or maintaining your facility, like leaking flanges.  If you can’t make your flanges up to where you can turn the bolts before you tension the belts, it could be because your pipe supports are putting some stress on it.  If you have continual bearing failures, it is because the weight of your pipe is on your process equipment.  Pumps, compressors, and vessels are not designed to carry the load of the pipes.  It’s important to make sure they are functioning correctly.  If you’re having problems like water hammer, bearing failure, or anything else along those lines, you should check your pipe supports. 

If you have any questions or problems feel free to call us, visit our discussion forum, or email us at info@pipingtech.com.  We have a guarantee 30 minute emergency response available 24/7 for your urgent needs. 

 

 

 

 

 

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Mailing: P.O. Box 34506, Houston, TX 77234-4506 Location: 3701 Holmes Road, Houston, TX 77051
Our Subsidiaries: U.S. Bellows: Metallic & Fabric Expansion Joints, Bellows
Sweco Fab: ASME Vessels, Pig Launchers, Spectacle Blinds
 Pipe Shields: Pre-Insulated Pipe Supports, Slides, Guides & Anchors

Fronek Anchor/Darling
: Snubbers, Sway Struts & Sway Braces
Phone: (713) 731-0030 Toll-Free: (800) 787-5914 FAX: (713) 731-8640 info@pipingtech.com

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