This Webinar will focus on the different types of variable spring supports and big ton variable spring supports. Learn about the special features available, in addition to the design of a variable support. View how the different coil configurations produce a unique response to an applied load and see how a spring assembly is loaded. Discover the basic steps in selecting a hanger design and the step by step process used to size a spring for your application.
3. Piping Technology & Products, Inc. Presents Variable Spring Supports and wholly owned subsidiaries: US Bellows Sweco Fab Pipe Shields Anchor/Darling Ent.
4. PT&P and Subsidiaries U.S. Bellows, Inc. Metallic Expansion Joints Thin-Wall and Thick-Wall Rectangular Expansion Joints Fabric Expansion Joints Slip-Type Expansion Joints PIPING TECHNOLOGY & PRODUCTS, INC. - Engineered Pipe Supports - Variable, Constants, Big-tons - Vibration Control Devices – Snubbers, Sway Struts - Support Assembly Components – Clamps, misc. Hardware - Pre-insulated Pipe Supports – Cryogenic/cold & Hot Applications - Fabricated Pipe Shoes, Guides & Anchors - Slide Bearing Plates - Anchor Bolts, Embed Plates IAS Certified, Member of MSS, SPED, APFA Member of EJMA SWECO Fab, Inc. Pressure Vessels Pig Launchers/Receivers Spectacle/Line Blinds Instrument Supports ASME/Misc. Fabrication ASME U-Stamp & R-Stamp Pipe Shields, Inc. Insulated Pipe Supports Commercial & Light Industrial Heavy Industrial – Base Mounted Types, Anchors Pipe Riser Clamps ISO 9001-2000 Certified Fronek A/D Ent., Inc. Hydraulic Snubbers - Short & Adjustable Strut Mechanical Snubbers dynA/Damp Compensating Strut ASME Nuclear Certified
5. Calculate hanger loads due to piping weight Calculate thermal movement of piping at each hanger location Determine hanger locations Select hanger type Check clearances 1 2 3 4 5 Spring Hanger Design Basic Steps in Spring Hanger Design
6. 1.) Relatively small thermal deflections, usually less than or equal to 2" are anticipated 2.) A difference in the supported load from the installed to the operating condition is acceptable Variable Spring Supports Characteristics
11. F-Type Variables with Fully Adjustable Travel Stops Variable Spring Supports Type F Type F F-Type Variable with Unique 3-Coat Paint System 23" F-Type Variables with Rollers
12. G-Type Variable Springs with Chained Travel Stops Variable Spring Supports Type G Type G G-Type Variable Springs G-Type Variable Springs
13. Variable Spring Supports Design Features: Spring Size & Load Capacity Height O.D. Wire Dia. Pitch
14. Total Deflection = ½ ∙ Y Total Deflection = Y Total Deflection = 2 ∙ Y Total Deflection = 3 ∙ Y Total Deflection = 4 ∙ Y Variable Spring Supports Design Features: Spring Configurations
15. Spring Supports Load & Travel Table Variable Spring Supports Spring Sizing Spring Supports Load and Travel Table
16. Step 1: Determine a theoretical spring rate ∆ Load / Movement Given the following design parameters: A.) Operating Load: 3000 B.) Installed Load: 3300 C.) Movement: ½" 3300-3000 ½" 600 Step 2: Review Load and Travel Table Chart Variable Spring Supports Spring Sizing
17. VARIABILITY = (Spring rate ∙ movement ) /Operating Load Step 3: Review Load and Travel Table Chart Step 4: Check Variability Factor VARIABILITY = (600 ∙ ½") / 3000 0.1 equal to 10% ≤ 25% Final Answer: PTP-2-130 Variable Spring Supports Spring Sizing
18. Check Hot & Cold Loads Compress Spring to Solid and Release 3 Times Zero out Load Cell Compress Spring to Cold Load Mark Cold Location on Can Measure for Travel Stop Length Compress Spring to Hot Load Variable Spring Supports Spring Loading/Assembly
19. Mark Hot Location on Can Measure Distance Between Loads Should Match Desired Travel Compress Spring to Cold Load & Place in Travel Stops Release Load and Check Travel Stops Remove Spring & Move to Table Using Hoist Variable Spring Supports Spring Loading/Assembly
20. Add Name Tag and Straps Drill & Hammer Rivets into Place Measure the Remaining Slot for Hydro-Test Stops Put Stops in Place & Strap Them Down Last Step: Measure and Adjust Load Flange Height if Necessary Variable Spring Supports Spring Loading/Assembly
21.
22.
23. Big-Ton Spring Supports Development of the Big Ton Innovation and customer service enabled PT&P to carve out a niche in the pipe support industry. The development of the "Big Ton" provides an interesting illustration of this. A customer asked PT&P if there was a way to support a large vessel that would be both stable and economical. PT&P responded by designing the big ton in 1980, which is essentially a table atop muscle springs. Top Load Flange Bottom Load Flange Load Studs Division & Centering Plates Travel Stop Rods Spring Pressure Plate Housing Load Stud Nut Coil Spring
24.
25.
26.
27. Big-Ton Spring Supports Application 120,000 lb. Load Big Ton Springs for a Large Diameter Elbow
28. Installation Guidelines Attachment to Structure F-Type Bolted to Structure F-Type Welded to Structure B-Type with Beam Clamp C-Type with a WT
32. Average life expectancy of: 10 years 20 years 30 years Unprotected Spring Hanger Galvanized Hardware Neoprene Coated Springs Maintenance Useful Life of a Spring Hanger
33.
34.
35.
36. Field Examples/Tips Visual Inspections: Out of Adjustment Increase of Load Required Decrease of Load Required Balance of Load Required
48. www.pipingtech.com Fatigue Testing Pressure Balanced Expansion Joints FEA: Plate Thickness and Pipe Stress Inspection and Maintenance of Supports “ Over 450 Project Examples” Value-Added Services Technical Literature Online
49.
Notas do Editor
Display this slide before the presentation begins, while viewers are joining…. Do not say what is on slide…. Switch to next slide before welcoming
Hello everyone, I would like to welcome you to our Webinar on Variable Spring Supports. The Webinar today is hosted by Piping Technology & Products. I am Jerry Godina and I will be your presenter. Also, if you have a question, please feel free to chat it to us during the presentation in the text box you see to the right of the presentation or if you prefer, you can ask questions after the presentation during our “Questions and Answers Session.”
For those of you who are unfamiliar with PT&P, I want to quickly go over some background information. If you would like to know more, please visit our “About Us” section at pipingtech.com. Our parent company, Piping Technology & Products, Inc., also known as PT&P, is a member of MSS, SPED, and APFA In business since 1975, Piping Technology & Products, Inc. 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 engineered pipe 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.
Pipe Hangers are designed to control: Longitudinal weight stress in the piping system without creating additional stresses Piping system loads on equipment without limiting or reducing static loads Hanger loads on building structure And physical clearances of hanger components with piping and structure Let’s look at the basic steps in the hanger design: Step 1 is to determine the location of all the hangers Then calculate the hanger loads due to the piping weight Next calculate the thermal movement of the piping at each hangers location Step 4 is to select the hanger type and finally check all clearances
Variable spring supports are used where: 1.) Relatively small thermal deflections, usually less than or equal to two inches (2 " ) are anticipated. AND 2.) A difference in the supported load from the installed to the operating condition is acceptable. We carry a substantial amount of variable springs in our inventory which can accommodate loads up to five-thousand pounds (5,000 lb.)
Variables use coiled springs to support a load and allow movement The resistance of the coil to a load changes during compression, which is why these devices are called “variables” There are many different designs for variable supports, we use A through G to describe seven different physical connections to the supporting structure. A-E and G are hangers suspended from structural members and type-F is a base support that rest on the supporting surface. All our variables are available in short springs, standard springs, double springs, triple springs or quadruple springs.
Type A variable spring supports are furnished with a threaded bushing in the top plate, providing for a simple rod attachment for the upper connection.
Types B and C variables are furnished with one or two lugs welded to the top cap plate of the casting.
Type D variable permits adjustment from the top, by turning the nuts on the hanger rod against the load column which protrudes through the top. Type E variable spring permits rod adjustment from either above or below the spring. This type of spring can be set above the supporting steel.
Type F is designed to support piping from below, directly from the floor or supporting steel. The base plate is bolted to the case and has four slots for fastening. An interesting feature of F-type variables is that the installed height can be adjusted independently of any load adjustment.
A type G spring support assembly is formed by welding two standard spring assemblies to the ends of a pair of channels. This type of variable can accommodate unusually heavy loads and is adaptable for avoiding interference in spaces where headroom is limited. Travel stops are inserted and strapped in place to maintain the load for the assembly installation. The “g-can” pictured here was manufactured for a Petrochemical Plant. As a side note, you may notice that the travel stops have been chained to the spring housing. This is an optional feature available on all spring supports which prevents loss of the travel stops after the assembly is put into service.
We have 44 different standard coil sizes, this is just a sample of the coils pictured here. Size range: 00-220
The way a variable spring support responds to an applied load depends on the coil or coils inside the casing. Each coil arrangement has a spring rate expressed in units of pounds/inch (or kilograms/millimeters) of compression. The required coil size is determined by load while the required number of coils (length) is determined by the anticipated range of movement. A longer coil or coils placed in series will provide greater travel for similar loads. We use PTP-1, PTP-2, PTP-4, PTP-6, and PTP-8 to designate the five standard coil arrangements we employ to increase the working range of travel of variable supports.
The Load and Travel Tables are color-coded to identify the travel and spring rates for each PTP figure number.* These tables can be used to select the PTP Figure Number and size required for a particular application. The twenty-three columns designated 00, 10, 20, ..., 220 identify the size and spring rate of coils used in the variables. The larger numbers have higher spring rates and are used to support greater loads. The recommended working range of loads for each size is shown between the red lines in the tables. The center of the working range is colored blue. Selecting variables with the loads within the working range provides a reserve above and below to insure the coil can function inside the casing. In using the Load and Travel Table to choose the proper variable support, it is best to have the operating (hot) load and an amount and direction of expected movement. Variability is a key criterion in selecting the figure number and size.
Example: Given the following design parameters: A.) Operating Load: 3000 B.) Installed Load: 3300 C.) Movement: ½ " Step 1: Determine a theoretical spring rate: ∆ Load / Movement (3300-3000)/ ½ " 600 Step 2: Review Load and Travel Table Chart
Step 3: Review Load and Travel Table Chart Step 4: Check Variability Factor Variability is the percentage of change in the supporting force between the operating (hot) and installed (cold) positions calculated as shown: VARIABILITY = (Spring rate * movement ) /Operating Load VARIABILITY = (600 ∙ ½") / 3000 0.1 equal to 10% ≤ 25% Final Answer: PTP-2-130 Good practice, as specified by MSS SP-58, is to choose a support with variability less than or equal to 25%. Always try to choose a variable with the operating (hot) load near the center line (blue) of the working range in the Load and Travel Table. If you have a situation in which you cannot select a standard variable which has both the operating load and the installed load within the working range, contact us and we will help you determine alternatives.
For the next three slides, we will go through the steps in loading a spring can. This particular spring can has a cut-away view for demonstration purposes. The first step is to check the hot and cold loads on the assembly drawing. The second step is to compress the spring to solid and release three times total. Then you will need to zero out the load cell before you compress the spring to the specified cold load. Mark the cold load location on the can, then measure for the travel stop length. Next you will need to compress the spring to the specified hot load.
Mark the hot location on the spring can, then measure the distance between load. The distance should match the desired travel. Compress the spring to the cold load and place the travel stops in. Release the load and check the travel stops. Remove the spring from the cage to a table using a hoist.
When adding the name tag and straps, first you need to drill and hammer the rivets into place. Measure the remaining slot for hydro-test stops Put the stops in place, strap them down, measure and lastly, adjust the load flange height if necessary.
Standard Features -Load Flange -Load Tag: Both Hot (red) and Cold (white) Movement -Installation Instructions -Travel Stops -Hot-Dipped Galvanize Finish -Adjustable Load Column (F-Can) -Pre-Loaded Left Picture: Type B Variable Spring Hanger Right Picture: Type F Variables designed for an offshore oil rig: carbon steel with hot-dipped galvanized components (PTP-6, size 90, 3 spring coils with a 7-1/2" working range, load capacity: 950 lb., overall height: 33-1/2", travel range: 4", 8-5/8" diameter casing, 13" square base plate, 8" load flange) http://www.pipingtech.com/news/arc_pw_2004/engps2004_04.htm
Special Features can be provided if required: --lifting lugs can be helpful for installing large hangers --Upper and lower limit stops --Collars --Special Paint --Guided load columns --Extended load columns --Chained travel stops --Jacking Bolts --Type F PTFE, 25% glass filled
“ Big Ton” is the name PT&P uses for a special type of variable spring support which was developed for the petrochemical industry. Many of these supports have been in service for more than 20 years. A typical big ton will have a rectangular array of coil springs supporting a pressure plate which in turn support a top load flange. Big tons provide the designer with options that are not available with typical spring supports, because they can support vessels and other components which have piping attached to them. The piping designer can choose to support these components and thus reduce loads which would be transferred to the piping. This is often a more economical and stable design for the entire systems. This type of support is used where two important characteristics in spring supports are necessary: - Extremely stable: Base supports springs of this design are frequently used under horizontal pressure vessel saddle supports in combination with slide plates or roller supports. Our Big Ton design lends itself ideally to this support situation. Type-F design is sufficient where there is a minimal amount of lateral movement, but where the combination of heavy loads and thermal expansion are required, big ton industrial springs should be your choice. Heavy Loads: The big tons’ multi-spring design lends itself to supporting very high loads. Loads up to 200,000 pounds can be handled with no problems. Big ton springs are custom designed to meet load and travel requirements for very large loads using a multiple coil system. Usually a base-mounted support that can be designed with slide plates for lateral pipe movement. The height, width and length are also custom designed to meet space requirements. Note: division & centering plates divide 2 coils stacked on top of each other and the little guides in side that holds spring in place
1 st Picture: base measures 63" square and the top load flange measures 55" square. One of the springs has an overall height of 22-7/16" and the other has an overall height of 28-5/8". Both big ton springs are custom designed and fabricated from carbon steel with a hot-dipped galvanized finish. The top of the load flange is covered by a stainless steel slide plate. One of the big ton springs is designed with a operating load of 126,000 lb. and the other with an operating load of 225,000 lb. Prior to fabrication, all of the coils, within the frame, were individually tested to insure correct spring rate and load capacity. After the units are fabricated, the entire assembly is tested throughout the entire load/travel range.
Top Picture: 8 foot long big ton variable spring assembly designed for a local area refinery Fabricated from carbon steel components with a painted finish, Top of load flange has three PTFE, 25% glass filled slide plates, Base is 96 " x 18 " and installed height is 24 " Operating load: 76,800 lb. and downward travel: 0.894 ", Prior to fabrication, each of the coils were individually tested to insure correct spring rate and load capacity. After fabrication, the entire assembly was tested throughout the entire load and travel range. Bottom Picture: Example of a “mini” big ton where loads/movement matched standard spring, but overall height was restricted Standard variable spring could not fit; solution was to use combination of smaller (shorter) coils which matched load carrying capability; short overall height could be maintained Right Picture: Dimensions: 42" x 36" x 32" Load: 25,400 lb. Movement: 7/16" Upward Spring Rate: 4400 lb/in. http://www.pipingtech.com/news/arc_pw_2008/engps2008_02.htm
As mentioned earlier, shipping complete assemblies helps with ease of installation in the field. - The plant supervisor called us in a panic because he could not find the big tons at the site. - The supervisor searched and searched for disassembled parts for a spring, all the while stressing about assembling it before installing it. - We sent a field service technician out to assist, and he found the big ton was already installed. - The supervisor was shocked, he said, “It never crossed my mind, that it was already installed, We are not used to complete assemblies arriving ready to go.”
While installing, securely attach the spring to the existing structure per the spring support design.
If required, attach a hanger rod to the fabricated load column or turnbuckle.
After hydro-testing, remove the travel stops as pictured here.
And the last step in installation is to verify that the load indicator is at the desired setting (cold/hot load)
Let’s look at the average life expectancy of a spring hanger: An unprotected spring hanger will last anywhere between fifteen (15) and twenty (20) years. If the hardware is galvanized, which is PT&P’s standard, the spring hanger will last between fifteen (15) and thirty (30) years. And if the springs are coated with Neoprene, it will last fifteen (15) to thirty (30) years. Corrosion and fatigue are the main factors that contribute to the deterioration of a spring hanger assembly.
If the piping system has inadequate support, static loads can cause multiple problems, like: Leaking flanges Pump and turbine problems, mainly concerning the bearings, seals and misalignment of flanges Sagging lines and/or liquid trapped in low sections And an increase in system stresses can result in piping failures as well
When inspecting a spring support, the first thing you want to do is: Visually inspect each spring hanger in accordance with the ten point operational integrity check which is pictured here. After the ten-point visual inspection, you should tag each spring hanger as good, adjust, or replace then issue a field summary report.
In the case you want to use your existing spring support, re-calibration is an option as long as the support is a constant spring support, in good operating condition, has an operating load range greater than fifteen thousand (15,000) pounds and the cost of field time and equipment is less than the cost of a new spring hanger.
Again, this support on the left is out of adjustment and the slide plate is no longer attached to the load flange. Note that these supports are not fabricated by PT&P. Pictured on the right is a C-Type variable spring support with the travel stop left in. Failure to remove the travel stops would lock the spring coil in position and render the support inoperable.
Again, this support on the left is out of adjustment and the slide plate is no longer attached to the load flange. Note that these supports are not fabricated by PT&P. Pictured on the right is a C-Type variable spring support with the travel stop left in. Failure to remove the travel stops would lock the spring coil in position and render the support inoperable.
To adjust a spring hanger after inspection, set to the desired position by turning the turnbuckles and load column. When the nameplate is present indicating the design hot load, adjustments can be made during operation, but a cold load adjustment needs to be made during a shutdown.
When deciding on whether to replace a spring can or not, consider the corrosion, fatigue, rust damage, and the modification of surrounding equipment and piping.
The above examples are indicative of supports which show limited functionality. The pair of base-type springs on the left exhibit significant rusting of the spring coil. Extensive deterioration of the coils would alter the spring rate and ultimately reduce the load carrying capability of the assembly. The two examples on the right show variable spring assemblies which have not been loaded. The load indicator at the top of the slot is a clear indication that either 1.) the springs have been unloaded and never returned to service or 2.) the assemblies were improperly sized for the load.
Pictured here are non-PT&P supports our field service technicians found in the field. Notice in both examples, the load indicator scales are missing or painted over. While it can be stated that the supports are taking load, it is extremely difficult for field personnel to distinguish the precise load these assemblies are holding.
A few thoughts during shutdown: Are the lines and equipment temporarily supported while repairs are being made? To prevent having to readjust the spring, I need to re-install the travel stops. If the name plate is missing, stencil the proper installed and operating positions or provide loads for re-calibration.
Our engineering and design department is involved in the following processes: -Piping, Pipe Support and Structural Design -3D Modeling Technology -Pipe Stress Analysis, in which we use Caesar II -For Structural Analysis, we use STAAD II -Our engineering and design department uses Finite Element Analysis for many projects: -FEA is used for Special Stress and/or Thermal Problems -It is used in 3D Part Design -They use ANSYS for Mesh Generation and Analysis and Results Analysis -Our Engineering and Design department is also involved in Field Testing.
PT&P offers on-site installation guidance, inspection and/or maintenance of pipe supports and snubber inspection. We carry a system of stock standard items and have an “on-call” engineering team available 24x7.
Remove this slide… does not flow when talking about services and then stopping and switching to an example
Since we don’t have much time this evening, you may want to check out our website; there you will find a plethora of technical information, including different Tests we carry out, FEA Analysis, and much more.
That concludes our Webinar on Variable Spring Supports…. I hope everyone enjoyed the presentation and as a reminder, we have a staff of experts standing by to answer any questions you may have. You can just chat them now while in session until the end of the hour, you can also send them to us by e-mail at info@pipingtech.com, or you can visit our discussion forum and post your question there, just click on the blue graphic labeled “DISCUSSION FORUM” on the left hand side of our home page at www.pipingtech.com