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BY JAMES L. GOSSETT

Refiners today are increasingly dealing with more corrosive feedstocks that present new demands on valves in the process. However, maintenance personnel can detect problems before they become major issues by using different testing methods.

In 2009, a Minnesota-located refinery was experiencing through-wall leakage with several Class 300 rotary valves tasked with controlling crude unit vacuum prefractionator charge heaters. Maintenance personnel removed insulation from the valves and noted coke residue on the surface of the valve bodies, which identified for them where the leaks were occurring (Figure 1).

Figure 1. Removing insulation from around the ball valve in question revealed leakage locations.Fortunately, this particular situation did not result in a safety event or a fire. Instead, it illustrates how the refining industry’s use of increasingly corrosive feedstocks can combine with unknown casting defects to cause potential valve problems.

THE INVESTIGATION/ EVALUATION

Five valve body castings, all grade CW2M (cast alloy C), were returned from the refinery to the manufacturer for evaluation using both nondestructive and destructive tests.

The nondestructive tests performed on the returned castings included visual examination, pressure testing and liquid penetrant (LP) examination.

Visual examination did not reveal any signs of corrosion on the wetted casting surfaces of the returned valves, which included both as-cast and machined surfaces.

The pressure testing used water at 1125 psig (7.76 megapascals or MPa) followed by helium at 150 psig (1.0 MPa). LP testing was performed to the requirements of ASTM A903 Level III, which considers linear and rounded indications exceeding 3/16 inch (4.8 millimeters) to be relevant. The helium and hydrostatic water tests revealed no leaks. Apparently, the hydrocarbon or potential coking sealed the leak paths once the valves were brought down to ambient temperature and removed from service.

LP testing of the castings revealed indications on the exterior surface—a lesser number of indications were on the interior, cored surfaces. These indications were on both as-cast and machined surfaces. Most of the LP indications were shallow [<0.02 inch (0.5 millimeters)] and removed with minor grinding. However, on the neck area of some castings, grinding did not remove the indications. The defect progressed through the wall of the casting and could represent a leak path. (Note that all of the returned valves had through-wall leaks in the neck area.)

Destructive testing, including metallographic examination, scanning electron microscopy (SEM) and energy dispersive spectrographic analyses, was performed on several of the returned castings.

Figure 2. Opened defect showing three zones of fracture. Original magnification 11x. For example, corrosion testing was done on one valve body casting to compare results to maximum acceptance values previously set for this material grade. The test environment was boiling ferric sulfate-sulfuric acid per ASTM G28 Practice A. Although this standard is intended for wrought product forms, the practice A test method is also useful for castings. The corrosion rate was 140 milli-inches per year or mpy (3.5 millimeters/year or mm/y) compared to the manufacturer’s acceptance criteria of 360 mpy (9.1 mm/y) maximum. The grain boundaries were visible, which is typical for this grade. Of importance to this issue is the fact that this is a very severe test that does not represent actual applications for CW2M but does detect susceptibility of weld metal and heat-affected zone to intergranular corrosion attack.

Figure 3. Rounded dendrite fingers indicating a shrinkage defect. Original magnification 600x.Fracture surfaces from the neck area of the same valve body were examined using SEM (Figure 2). The first zone examined was an outer layer that was approximately 0.03 to 0.06 inch (0.8 to 1.5 millimeters) thick. This chill layer solidifies rapidly when the molten metal first contacts the mold surface.

The second layer or zone 2 of the fracture has a dendritic pattern. This pattern represents columnar grains that grew perpendicular from the chill layer during the balance of the solidification process. The neck was cast solid so all the grain growth was from the outer diameter to the center. The center of the neck was then bored out during machining of the casting.

Zone 3 was ductile, dimple shear. This is the fracture mode seen on any mechanical break produced in the lab.

Within the dendritic zone of some of the fractures were rounded dendrite arms (Figure 3). The rounding indicates a shrinkage defect caused by an isolated area of liquid that was frozen off from the riser system because it was not properly fed. When the liquid was consumed during solidification, the dendrite arms could not continue to grow, leaving the blunted tips. Dark areas, which were identified as oxide films formed from exposure to air during casting solidification or heat treatment, were also found on the lab fractures. This proves the fractures were present before the casting went into service.

Figure 4. Photomicrograph showing the leak path and the continuation of the grain boundary. Original magnification 500x.Inclusions and porosity also were visible. The inclusions were mold sand, slag and oxides. The grains were very large compared to wrought product forms—about 1/4 to over 1/2 inch (6 to 13 millimeters). The grain boundaries were the intersection of the dendrites formed during solidification. One leak path was cross-sectioned (the photomicrograph in Figure 4 shows the continuation along a grain boundary).

University of Houston Professor Michael J. Economides told the PVF Roundtable at its Feb. 21 meeting in Houston that oil, gas and coal will satisfy U.S. energy needs for years to come. Further, he called the Obama administration’s emphasis on alternative energy sources misguided.

“World demand for energy coming from fossil fuels is 87%. In 2030, world demand for fossil fuels will be 87%,” said Economides, who is a professor of chemical and biomolecular engineering. “Solar and wind power will never provide more than 1% of world demand for energy. Wind power has been exposed as expensive, and it won’t save energy costs.

“There are no alternatives for hydrocarbon fuels in the near future.”

In contrast, he noted, projected growth of natural gas as an energy source will average 7.36% per year worldwide to 2035. By the same year, almost half (49%) of the natural gas in the United States will come from shale.

 The U.S. Energy Information Administration estimates the United States has more than 2,500 trillion cu. ft. of technically recoverable natural gas, of which 33% is held in shale rock formations.

“Shale gas is great for the United States,” Economides said. “Innovative technology made shale gas a reality.”

Drawing a connection between energy consumption and wealth, he said the United States is the world’s biggest energy consumer.

“A rich country will use more energy,” Economides said. “Use of energy generates wealth.”

The PVF Roundtable’s next meeting will be May 15 in Houston. It will be preceded on May 14 by the PVF Don Caffee Memorial Scholarship Fund Golf Tournament. For more information, visit www.pvf.org. 

Here are more photos from the Feb. 21, 2012 PVF Roundtable.

HD Supply agreed to sell its industrial pipe, valves and fittings  business to Shale-Inland Holdings, an affiliate of investment firms TowerBrook Capital Partners and The Stephens Group. The purchase was expected to close in March. The purchase price was not disclosed.

“After careful evaluation, we determined that divesting our industrial PVF business is in the best interests of our company as we seek to continue strengthening our industry-leading businesses,” HD Supply CEO Joe DeAngelo said.

Once the sale is complete, proceeds from the transaction, according to the company’s announcement, will provide HD Supply with additional financial and strategic flexibility to further strengthen its portfolio. As of Jan. 9, 2012, the Atlanta-based distributor had approximately $1.2 billion in available funds. This liquidity “provides ample capital to fund growth and meet its financial obligations,” the company said.

Last September, the company sold its plumbing/HVAC business to Hajoca Corp.

Janesville, Wis.-based welded, stainless-steel and alloy tubing manufacturer RathGibson agreed March 8 to be acquired by Precision Castparts Corp. The deal is pending regulatory approval. Precision Castparts – based out of Portland, Ore. – is a worldwide manufacturer of metal components and products in the aerospace, power and general industrial markets.

RathGibson CEO Mark G. Essig sees a strong future for RathGibson with its new business partners. “Operating as part of PCC will allow RathGibson to accelerate its growth plans and offer a more complete product capability to the market. We look forward to capitalizing on the opportunities that this strategic partnership will offer,” he said.

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Triple offset valves provide an efficient solution for critical and non-critical applications when positive isolation is required in upstream oil and gas operations. Their compact nature offers savings in weight and space and most importantly, cost.

Most onshore and offshore installations traditionally use ball valves and occasionally gate valves for the majority of flow isolation applications. Specifications typically call for 6D valves, but engineers seldom look beyond these specifications to other valve types with similar or better performance.

Many of these engineers are not yet aware that in many offshore isolation applications, a triple offset valve (TOV) offers benefits in terms of weight, overall dimensions and performance versus the standard ball or gate valve. A TOV can be the right choice for applications in the turret of a floating production storage and offloading vessel (FPSO), and in virtually all topside process applications of FPSOs and platforms such as separators, water treatment, gas compression and other systems.

Today’s TOVs, with pressure ratings up to ASME Class 1500 and zero leakage, cover enough applications to achieve significant savings in weight and space, as well as total cost of ownership.

HISTORY

The TOV design was introduced in the early 1970s as the next great development after the high-performance butterfly valve. The design is totally different from conventional or high-performance butterfly valves, however, offering a 90-degree non-rubbing rotation and metal-seated zero leakage.

Since the TOV was introduced, it has become a success with end users in the downstream oil and gas, process and power industries. It is recognized as a reliable, robust and valid alternative to gate and globe valves as well as ball valves.

The TOV concept is applied in a wide variety of applications from cryogenic to high temperature and from low- to high-pressure where positive isolation is required. Since its introduction, more than 500,000 TOVs have been installed worldwide with an extremely wide range of sizes and ratings and different materials—from WCB to duplex and from CF8M to titanium.

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The Barnett Shale petroleum drilling site located in North Central Texas.

The increasing focus on finding ways to depend less on foreign energy sources, coupled with the huge shale plays now available to U.S. and Canadian energy producers, is good news for the valve industry. However, with gas prices at near-record lows and lingering questions about the environmental impact of fracturing, challenges lie ahead.

The recent increase in shale gas production in the U.S. and ­Canada, made possible largely by technological advances, has meant access to reserves nearly impossible to tap a mere five years ago. For energy producers, as well as valve, actuator and control manufacturers and distributors, this access creates potential for profitable exploration. For consumers, it means a relatively inexpensive source of clean energy not subject to the whims and vagaries of politically unstable countries.

Still, while low natural gas prices are a boon to consumers and utilities, those lower prices have created a real challenge to producers over the past year. As of mid-February 2012, prices were hovering around $2.50 per thousand cubic feet, necessitating cutbacks in the Marcellus shale area and making it less viable to drill in more remote locations like Haynesville and Barnett. Several companies have recently announced intentions to either reduce the number of new wells drilled or reduce production at operating wells.

However, prices that go down will eventually come up, and with them, production rates will rise. In the meantime, unconventional natural gas producers and those who supply the industry continue to develop more efficient exploration and production methods, engineer more robust materials and implement special practices that balance economic viability with environmental responsibility.

THE CHALLENGES

So what challenges does this lucrative industry face?

Economics and Water Use

Mike Romano, global market manager, Unconventional Oil and Gas, Tyco Flow Control, says that the recent drop in gas prices is one of the most significant challenges to unconventional gas production today.

He points to the decoupling of gas from oil prices.

“Spot prices have dropped from around $12 per million British Thermal Units (BTU) in 2008. Now they’re at $2.50. Oil went down from $130 to $70 per barrel, but came back up to $100. Before, when gas or oil prices went up, the other followed, but when shale gas came into play, the prices started going in different directions.”

Why did this happen? Romano says because of lower demand caused by the financial crisis compounded by dramatic growth of gas production through new technologies.

Another challenge to the industry today is water management. Hydraulic fracturing for a typical horizontal shale gas well takes about 4.5 million gallons of water. Detractors of fracturing have accused producers of depleting the drinking water table even though companies such as Chesapeake and Encana have made it a practice to steer away from potable water use. In addition to using untreated water from rivers, creeks, lakes and groundwater, they use discharge water from industrial or city wastewater treatment plants. The fracturing industry also has adopted the practice of reusing frac water to lower consumption of new sources.

While the overall mix of water sources depends on the region, the costs associated with transporting water in and out of a site can be as much as $1 per barrel, a sizeable incentive to reduce water use and recycle whenever possible.

In addition to the water source controversy, the fluid used in the fracing process, which is comprised of water, sand and some chemicals, must be extracted from the well and either recycled or disposed of through proper channels. Surface water discharges of this flowback are regulated by the National Pollutant Discharge Elimination System program under the Environmental Protection Agency (EPA), which requires flowback to be treated before discharge into surface water or underground injection be treated before its discharge. Underground injection of flowback is regulated by either EPA’s Underground Injection Control (UIC) program or a state with primary UIC enforcement authority.

The problem was compounded recently when increased underground injection of frac wastewater was blamed for causing earthquakes near Youngstown, OH. Environmentalists used what happened to call for broader federal regulation and drilling mora­toriums. What effect this will have on continued development is yet to be seen.

Public perception

Butterfly valves in the field

In a recent interview on ValveMagazine.com, Chris Tucker, team lead, Energy in Depth (EID), pointed out that public perception is a major challenge facing the shale gas industry. [EID is a research, education and public outreach campaign launched by the Independent Petroleum Association of America in 2009. Tucker was interviewed for an article posted Feb. 9, 2012].

While valve manufacturers, producers and pipeline operators seek ways to reduce emissions, improve safety and reduce the environmental impact of hydraulic fracturing and natural gas transport, opponents have gone to great lengths to malign these efforts. EID addresses this issue through media education and public outreach programs, but negative publicity remains a constant battle.

Tigre USA announced the opening of a regional distribution center located in Americus, Ga., to better serve its PVC pipe fittings customers in Georgia, Alabama, Tennessee, Florida and the Carolinas. The distribution center stocks SDR 35G and SDR 35S, Schedule 40 Pressure Fittings and DWV Fittings. 

“With our new distribution center, Tigre is responding to regional customer demand,” says Dago Darezzo, Tigre USA’s logistics manager. “Tigre can now offer fast local distribution for the plumbing, irrigation, municipal and HVAC markets, improve our order fill rates and reduce lead times, all of which delight customers.”

The order process remains the same. All plumbing orders must be sent to Tigre in Janesville, Wis., with the exception of Georgia, Alabama and the Florida Pan Handle. For waterworks, all orders are still sent to Tigre.

In related news, the company has expanded Odum Sales’ territory — its sales rep in Georgia and the Florida Pan Handle — to include the state of Alabama for sales and customer service.

Source: Tigre USA Inc.

Tigre USA announced the additions of Bob Sapienza and Tim Johnson to the Tigre USA management team.

Sapienza is the director of Sales & Marketing for the North America Region, responsible in leading the sales and marketing actions, while maintaining focus on the company’s strategic goals for both Plumbing and Municipal segments. With more than 25 years of sales experience, he has worked with established brands such as Delta Faucet, Kohler Co., Jacuzzi, Kaldewei and Seagull’s private label division.

Tim Johnson

Johnson is the Marketing & Product manager for the North America Region. Johnson is responsible for Tigre USA’s overall marketing and strategic planning programs and has more than 15 years experience in marketing, sales and account management experience with both small manufacturers and Fortune 750 companies.

Both positions report to Fabricio Rubine, general manager of Tigre USA Inc. 

Source: Tigre USA Inc.

HD Supply has agreed to sell its industrial pipes, valves and fittings (PVF) business to Shale-Inland Holdings, an affiliate of investment firms TowerBrook Capital Partners and The Stephens Group. The purchase is expected to close in March 2012. The purchase price was not disclosed. 

“After careful evaluation, we determined that divesting our Industrial PVF business is in the best interests of our company as we seek to continue strengthening our industry-leading businesses,” said Joe DeAngelo, CEO of HD Supply. “The Industrial PVF team, with the expertise of its many seasoned industry veterans, has done a tremendous job, and they can be proud that this new chapter is the result of the momentum they have built and the success of their initiatives.”

Once the sale is complete, the proceeds from the transaction will provide HD Supply with additional financial and strategic flexibility to further strengthen its portfolio, according to the announcement. As of Jan. 9, 2012, the Atlanta-based distributor had approximately $1.2 billion in available funds. This liquidity “provides ample capital to fund growth and meet its financial obligations,” the company said.

Last September, the company sold its plumbing/HVAC business to Hajoca Corp.

Source: HD Supply

Janesville, Wis.-based welded, stainless steel and alloy tubing manufacturer RathGibson agreed March 8 to be acquired by Precision Castparts Corp. The deal is pending regulatory approval.  

Precision Castparts – based out of Portland, Ore. – is a worldwide manufacturer of metal components and products in the aerospace, power and general industrial markets.  

RathGibson makes precision engineered straight lengths, coil and U-Bend tubing for the power generation, oil and gas, chemical and beverage industry among others. CEO Mark G. Essig sees a strong future for RathGibson with its new business partners.  

“Operating as part of PCC will allow RathGibson to accelerate its growth plans and offer a more complete product capability to the market. We look forward to capitalizing on the opportunities that this strategic partnership will offer,” said Essig.  

RathGibson’s manufacturing plants are located in Janesville, Wis.; North Branch, N.J.; and Clarksville, Ark. (Greenville Tube). Sales offices are located in Janesville and North Branch, as well as, Shanghai, China; Mumbai, India and Vienna, Austria.  

Source: RathGibson