Expansion Joints
- May 07, 2021
During an initial expansion joint Preventative Maintenance and Reliability (PMR) Service performed at the paper mill, it was determined that several competitor joints required replacement. These pipelines carry water, pulp, black/white liquor, bleach, and CIO2.
Though recommended for replacement on the Garlock Preventative Maintenance and Reliability (PMR) report, the mill postponed purchase. To date, four of those items flagged for replacement have failed - with the most recent failure resulting in an administration building filling with 4 feet of pulp.
OPERATING CONDITIONS AT CUSTOMER FACILITY
- Size: Pipe- 1.5” - 48” ID
- Temperature: 70° - 250°F
- Application: Various throughout mill
- Media: Various throughout mill
- Pressure: Vacuum to 200psi
- January 20, 2021
The Style 204 family of spool-type expansion joints are manufactured with the industry standard narrow arch design. This style is intended to be used in dynamic conditions where both pressure and vacuum concerns are present.
OBSERVATION OF ISSUE(S)
A stainless hosing was used and would continuously fail due to abrasion on the leading edge of the hose. The hosing would last for 3 to 6 months before replacement.
COMPANY BACKGROUND
This chemical plant based in Southern United States produces fluid catalytic cracking (FCC) catalysts, cocatalysts and additives used by petroleum refineries to convert crude oil into gasoline, other transportation fuels, heating oil and petrochemical feed stocks. Kaolin based microsphere intermediaries are used to manufacture the FCC catalysts and
- September 11, 2020
Garlock Style 215 Helps Steel Products Manufacturer With Harsh Acids
Garlock Style 215 Expansion Joints are PTFE concentric spool-type flexible couplings that are designed to reduce noise and compensate for expansion, contraction, and minor piping misalignment in chemical processing, air conditioning, and heating systems.
The complete assembly includes a fluorocarbon resin PTFE body, electroless nickle-plated ductile iron flanges, polyethylene-covered restriction zinc plated bolts, and stainless steel corrosion-resistant reinforcing rings.
Case Study
INDUSTRY
Primary Metals
CUSTOMER
South American manufacturer of flat and long steel products
BACKGROUND
Construction of two new facilities including a hot rolling mill.
CHALLENGES FACED
The plant was in need of expansion joints that could handle chemicals on their pickling lines. Pickling is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals. A solution called pickle liquor, which contains strong acids, is used to remove the surface impurities. It is commonly used to clean steel in various steel making processes. The line required an expansion joint with a PTFE tube to handle the pickle liquor which included hydrochloric and sulfuric acid, but a very short overall length for installation.
- May 12, 2020
It’s no news that coal-fired generation is going by the way-side. Despite a recent resurgence in political support, coal is fighting an uphill battle on two major fronts: economically and environmentally. After the shale gas boom in the 2000’s, plummeting natural gas prices and rising environmental concerns have continued to make operating aging coal-fired plants less and less attractive – for owners and consumers alike. The recent slowdown issues with the pandemic are only exacerbating the conditions – as industrial and commercial sectors are the greatest consumers of electricity. With only the cleanest and most efficient plants left in operation (in 2010 coal generated 45% of the nation’s electricity, compared to 24% by the end of 2019) and the rest quickly moving towards eventual closure, we are witnessing a tremendous shift take place. So how is this shift going to resolve and what should we expect?
Long-Term Changes
Fortunately for us in 2020 – the shift away from coal has been happening long enough that new generation capacity has already been under construction and is coming online just in time to replace the retiring coal plants. The economic downturn effecting industry has showed an acceleration in these trends – but natural gas and renewable outputs have been rising to pick up the slack for over a decade. In fact, the U.S. has been somewhat lagging behind in terms of progress towards renewables with some European countries already shutting down the last of their coal-fired plants. Though domestic renewables are indeed growing significantly – having nearly doubled in power production in the past ten years, and are expected to double-over again and overtake natural gas by 2050.
- March 27, 2020
Facility Issue:
In a brine concentrator, an original competitor’s expansion joint failed upon start up.
Industry:
Water Treatment
Background of the Facility:
This facility is a Zero Liquid Discharge (ZLD) power plant. Water is initially pumped from a well, pre-treated, used as process water, then reclaimed and retreated with a Brine Concentrator for use in their cooling towers. No city water is used and no waste water is disposed of from the site.
Brine concentrators use thermal energy to evaporate water, which is subsequently condensed and discharged as clean distilled water.
Brine Concentrators are also used in water treatment facilities in desalination plants, mining operations and well drilling operations in the oil & gas industry.
- Size: 24 “x 10” FF
- Temperature: 221° F
- Media: Brine Slurry
- Pressure: 30 psi
Observation:
The original expansion
- January 21, 2020
Garlock Style 204 Rubber Expansion Joint
The Style 204 family of spool-type expansion joints are manufactured with the industry standard narrow arch design. This style is intended to be used in dynamic conditions where both pressure and vacuum concerns are present.
Features and Benefits
- Fully laboratory and field tested for long life and exceptional reliability
- High pressure and vacuum resistance offer increased safety and ensure suitability for a wide range of applications
- Single and multi-arch designs are available for a range of movement capabilities
- Concentric and eccentric reducing configurations can be provided to join piping of unequal diameters
- January 10, 2020
Pay careful attention to these possible rubber expansion joint issues
A rubber expansion joint is likely the least understood and most abused component in a piping system. They are flexible, stretchy, and easily forced into lots of places despite what the installation instructions say. Most of the time, rubber expansion joints are merely an afterthought in a multimillion-dollar piping systems - until things go awry.
The rubber expansion joint is unmatched for vibration isolation. If properly installed, a rubber joint can greatly reduce equipment nozzle loads. Its resilience allows it to be installed in many different systems under a range of temperatures, pressures, and media. What could possibly go wrong?
Blame Murphy's Law if you want, the fates, or the alignment of planets. The reality of most failures is more straightforward. Most of the time, it is installation. More specifically, not following the manufacturer's instructions. See Images 1 to 7 illustrating the ugly aftermath of ignored installation instructions and unforeseen operating conditions.
Learn these lessons well so your piping system does not become the subject of another article.
Respect the Dimensions
Sometimes flexibility is a disadvantage. Why? Because it is easy to compress a joint into a space that is too small, which is exactly the problem in this example. The bead was damaged as the joint was forced into a gap between flanges, resulting in a seal failure. Spherical expansion joints rely on this bead to form a seal between flanges. If the bead is damaged, the building engineer will curse your name for eternity. Do not violate the face-to-face dimensions of an expansion joint.
Alignment is Still Necessary
Pipes misaligned? Think a bendy, stretchy rubber expansion joint will fix the situation? Thank again. This joint was installed between two misaligned flanges. A typical scenario may look like this:
- Joint installed between two misaligned flanges
- Joint begins leaking at the flange-to-flang seal in a week (or month, or several months)
- Bolts tightened, leak stops. In the meantime, the rubber bead takes a compression set, becoming less resilient
- Repeat steps 2 and 3 several times
- Bead is compressed to about 1/16th inch, rips apart from the body, pump room is now a water park
Do not turn your pump room into a water park or, even worse, a sewage tank. Align those flanges before installing expansion joints.
Consider Steam Generation
Did you know water pumps can generate steam? This operator did not. In this unfortunate scenario (Image 4), the operator closed the pump isolation valves with the pump operating, dead-heading the pump. This situation is fine for a short duration, but eventually all that mechanical energy added to the water has to go somewhere. It went into heat. The water contained in the pump and pipe up to the isolation valves had so much energy added, that it flashed to steam. The expansion joint was the first component to fail, which was fortunate for the pump. The temperatures and pressures exceeded the rubber performance limits and the joint failed, nobly sacrificing itself for the greater good of the pump and piping.
- October 15, 2019
A flexible choice can adapt to permanent misalignment, preventing future damage.
Keeping aging facilities and equipment maintained is an ever-changing task that can jeopardize the goal of maximizing uptime. Years of thermal cycling, vibration or foundation settling can disorient piping or pumps. Piping engineers will use rubber expansion joints to account for these types of challenges in a rigid piping system. Permanent misalignment can set in after years of operation. The original-size expansion joint could no longer be the best fit when it comes time to replace.
Replacing a permanently misaligned expansion joint connection with the original part could lead to reduced service life and/or missed expectations of the new expansion joint. Determining the best way to accommodate this when it comes time to replace the existing expansion joint can have long-term effects on reliability. Since the original components may not fit in the newly disoriented flange connection, they are limited in their reliability.
Types of Customization & Benefits
Expansion joints are designed to withstand the pressure retention of rigid pipes, yet be flexible and absorb misalignment induced in these systems. However, there are limits to exactly how much flexibility can be absorbed before damage occurs. Using this flexibility to connect two misaligned pipe flanges will take away from how much movement can be absorbed during the actual operational period when the system is running.
Attempting to retrofit a standard-size expansion joint to connect a misaligned pipe connection can put excessive stress on the component and could lead to a shorter operational service life. For this reason, the Fluid Sealing Association (FSA) recommends no greater than ±1/8-inch misalignment of the pipe flanges during installation. Depending on the severity of misalignment, it can be advantageous to implement custom expansion joints to minimize the stresses that cause these joints to fail or become damaged during installation.
Maintenance crews can also benefit by having a component that will fit precisely. Concerns for safety are present when attempting to put enormous pressure to compress, elongate or offset the joint so it will fit in place.
Custom expansion joints, made-to-fit, provide long-term dependability and can be designed in many orientations. To prevent overexertion, expansion joints are often constructed to connect nonstandard distances between pipe flanges. Other modes of misalignment can connect pipe flanges that are no longer centered.Face-to-Face Tailoring
Years of cycling, wear and other factors can contribute to the disorientation of a particular pipe connection. The length of an expansion joint, a dimension commonly referred to as face-to-face, bridges the gap between two parallel pipe flanges. A common industry problem is created when foundations settle and piping support structures transition lower than where it was originally constructed (Image 1). Expansion joints are designed to account for this, but choosing the correct replacement will make the difference between continued reliable service life or system failure.
Stretching an expansion joint to fit the changed flange connection often results in immediate damage that is only sometimes visual to the naked eye. A stress point on the outer cover of the expansion joint will usually become visible at the transition corner between the flat portion and the base of the arch in the form of a crack. The severity of cracking, elongation and settling will be aggravated when pressure in the pipeline is turned on.
Depending on nominal pipe size, industry standards will include standard face-to-face sizes of 6, 8, 10 or 12 inches, according to the FSA. When a standard 6-inch face-to-face joint is removed, the length between flanges could have been elongated to 7 inches or more. Many expansion joint consumers are not aware of the capability to build the expansion joint to the required nonstandard 7-inch face-to-face since it is not a standard offering. Building the replacement expansion joint to the nonstandard 7-inch face-to-face will eliminate any initial stress imposed on the joint.
- January 29, 2019
Expansion Joint Control Units
Elongation settings are a vital factor to assembly effectiveness.
It is no secret that one of the greatest demands for an expansion joint is the expectation to serve a long, leak-free life with little-to-no maintenance. Once installed, these flexible rubber connectors should require little attention. The preservation of this investment (and one’s sanity) can be maximized with an in-depth overview of how control units can prevent a new expansion joint from being overstressed.
The purpose of a control unit is to act as a safety device against excessive movement resulting from pressure thrust. A typical control unit assembly is comprised of threaded rods, steel gusset plates, nuts and washers (see Images 1 and 2).
The usage of control units with an expansion joint is always beneficial; pressure spikes during a system upset can cause uncontrolled surges through the expansion joint. This is a prime example of how valuable it is to have control units installed to protect these rubber assets from damage.
Methods to the Madness
A common misconception about control units is that they are designed to support the weight of pipe members or act as a substitute for adequate mounting. They are not. The sole purpose of a control unit is to allow the expansion joint to move freely within a specific range of movement while preventing the joint from being overstretched from pressure thrust forces.
The control units in no way impede the joint from performing its other duties beyond movement (vibration absorption, cycling or compensation for misalignment). The few extra steps needed to install the control units with the expansion joint could pay notable dividends in the long run.
Pressure thrust plays a huge role in how an expansion joint functions. While under pressure, the forces acting on the inside walls of the expansion joint actually cause the joint to swell and elongate. In the real world, an expansion joint is held comfortably between two pipe flanges, which in most cases are restrained by a pump lagged to the floor or mounted to a structural beam. Although it may not be apparent to the naked eye, once the expansion joint sees pressure, it produces a thrust force that acts axially on both pipe flanges.
Theoretically, what would be the result if the expansion joint was unrestrained on each end while pressurized?
Without fixed ends, the pressure thrust would force the joint to elongate without bounds.
Most useful in high pressure applications, the control rods will engage with the gusset plates once a pre-specified amount of growth for the expansion joint has been reached, restricting the joint from stretching any further. At this point, the control rods are absorbing any additional thrust acting on the pipe flange, thus limiting the amount of stress that is exerted onto adjoining equipment.
The design theory for sizing control unit hardware is based on the pressure thrust. Nominal inside diameter (ID) and arch geometry of the expansion joint are key drivers for calculating the thrust force that will be applied to the pipe at maximum line pressure. Per
industry standards set by the Fluid Sealing Association (FSA), both control rods and gusset plates are designed to withstand no more than 65 percent of the yield strength of the material.
Magnitude of the pressure thrust can be calculated by knowing the internal pressure and the effective area of the expansion joint. Effective area is found using the arch diameter of the expansion joint, which takes into account the size of the arch.
For example, we can calculate the resulting pressure thrust for a 10-inch ID expansion joint using an arch height of 1.5 inches that is rated for a maximum pressure of 250 pounds per square inch (psi).
The equation for pressure thrust “T” is:
These design limitations based around yield stress are the reasons why some control units made from lower yield strength stainless steel contain thicker components or more rods per set than the standard carbon steel control units.
Installation & Inspection
For a control unit assembly to be effective, rod positioning and elongation settings are critical during installation. Each control rod should be evenly spaced around the flange to best distribute the load. Elongation settings (see Image 5) are often overlooked, yet are a vital factor to ensure the control units fulfill their intended use.
Every expansion joint comes with movement ratings based on arch size, configuration and number. These movement design ratings of the expansion joint are critical pieces of information that are absolutely required during the installation of control units. The general rule of thumb is the gap between the gusset plate and the nut should be adjusted to match the joint’s elongation rating.
Having this information at hand during installation is great, but what about the existing control units currently in operation? Visual inspections of these components are a basic task that goes a long way toward extending the life of the joint.
Here are the top 4 anomalies to look for when performing a field inspection:
- December 18, 2018
The ABRA-LINE™ family of products was developed for highly abrasive applications typically found in the power generation, fertilizer, mining and chemical industries. These may include flue gas desulphurization systems, phosphate mining, dry bulk power transfer systems, tailings and slurry applications. Our proprietary urethane formula was designed to reduce wear and extend
service life.Style 404 Expansion Joints are specially designed for full vacuum abrasive service applications. The tube material is a proprietary urethane formulation. Style 404 can be constructed as a single or multiple arch design. It can also connect pipe flanges in concentric or eccentric tapers, to join piping of unequal diameters.
Case Study: Chemical Processing
Industry
Chemical ProcessingObservation
A stainless hosing was used and would continuously fail due to abrasion on the leading edge of the hose. The hosing would last for 3 to 6 months before replacement.