HEBNA Compressed Fit HDPE Advantages:

  • Pre-engineered solution
  • NSF certified materials
  • Class IV fully structural solution with a minimum of a 50 year design lift
  • Designed per AWWA’s M28 Manual
  • Excellent flow characteristics
  • “Off the shelf” fittings available for HDPE repairs and connections
  • HDPE pipeline fits tightly into your existing pipeline, no grouting required
  • Fast, safe and economical solution resulting in a high quality, long lasting pipeline

HEBNA Compressed Fit Liner Installation Process Video

HDPE liners are custom made to exacting specifications by an extrusion process at an HDPE Pipe manufacturing plant. The liner is made to a size slightly larger than the inside diameter of the intended host pipe. Liner pipe is usually manufactured in discreet lengths, that will be fused together in the field. Smaller diameter pipe are sometimes supplied in reels that require far fewer fusion joints.

HDPE Liners

FIGURE 1

The fusion process is a critical step in the “installation” of an HDPE liner [see Figure 1]. HEBNA shields its fusion process from the wind and rain using a specially designed enclosure called a “tent”. The “tent” insures that the fusion process is carried out in a controlled thermal environment. An adequate heating and cooling period is required for optimal HDPE fusion [see Figure 2].

Shielding Tent

FIGURE 2

Using HEBNA’s Compressed Fit Liner System (HEBNA-CFL),  a liner’s outer diameter (OD) is reduced by pulling it through the hydraulically assisted compression system with a specialized winch or “wireline unit”. The compression system or “roller-box” is comprised of a series of progressively smaller rollers and dyes designed to reduce the OD of the  liner to a size slightly smaller than the inside diameter (ID) of the host pipe.  In the process, the HEBNA-CFL compression system reduces the amount of tension required to pull the liner through the “roller-box” thereby reducing linear stretching of the HDPE. Once the compressive forces exerted by the “roller-box” are released, the elastic properties of the HDPE liner cause it to elasitically rebound to its original shape and conform to the inner walls of the host pipe [see Figure 3].

HEBNA-CFL

FIGURE 3

HDPE flanges or “stub ends” are fused to the ends of each section of the HDPE liner. The stub-end is protruding past the end of the host pipe’s steel flange. Each section of the pipeline, with its new HDPE liner, is hydraulically tested after the steel flanges are bolted together to insure the integrity of the liner.

HDPE Flanges

FIGURE 4

CASE STUDY: COMPRESSED-FIT LINERS (HEBNA CFL)

Rehabilitation of a 70 Year Old Crude Oil Pipeline through the Heart of Oklahoma City using Compressive-Fit HDPE

Authors:

Joe Lane, HEBNA Corporation
Roberto Ogarrio, P.E., HEBNA Corporation

1. ABSTRACT

Among a major U.S. oil and gas company’s assets is a network of approximately 5,800 miles of crude oil pipelines. Located principally in Oklahoma and Texas, these pipelines date, in some cases, back to the 1940’s.

To comply with the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) regulations, these pipelines must comply with and follow an integrity management program. An integrity management is a documented set of policies, processes, and procedures that are implemented to ensure the integrity of a pipeline. Following this program, the pipeline must undergo periodic inspections. In one such assessment internal corrosion was found in a 55-mile section of a 70-year-old, 8-in-diameter crude oil pipeline that terminated just east of downtown Oklahoma City. The assessment indicated the pipeline would need to be replaced or rehabilitated before it could be returned to service.

At the time of its original construction, this pipeline had been routed through a mostly rural, sparsely populated region of Oklahoma. Over the past 70 years, however, the surrounding landscape has changed dramatically. In addition to farmland, the original route now passes through towns, suburban neighborhoods and a golf course, runs under roads and busy highways, and crosses rivers and streams.

This paper will describe the assessment, design and solution selection process that ultimately resulted in HEBNA Corporation’s installation of a compressive-fit HDPE liner in the aging pipeline, bringing it into compliance with PHMSA regulations. This paper will also discuss the construction process and the diverse challenges associated with the project, as well as lessons that other companies with regulated pipelines might learn from this oil company’s experience.

2. INTRODUCTION

Since 2004, hazardous liquid, gas gathering, transmission and distribution pipelines in the U.S. have been regulated by the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) Office of Pipeline Safety (OPS). PHMSA was created to ensure that our nation’s pipelines are safe, reliable and environmentally sound, PHMSA regulates pipeline construction, maintenance and operation. In the decade since the agency was formed, these regulations have grown increasingly stringent.

Most of today’s pipeline regulations did not exist in the 1940s, when the 8-in-diameter crude oil pipeline that runs from 55 miles north of Oklahoma City to just east of the city’s downtown was first installed. By the time the pipeline celebrated its 70th birthday, however, it was subject to regulations which called for periodic inspections to test the integrity of the pipeline.

Pipeline integrity, refers to a system that is in sound, unimpaired condition that can safely carry out its function under the conditions and parameters for which it was designed. An integrity management program is a documented set of policies, processes, and procedures that are implemented to ensure the integrity of a pipeline, and these plans are required within the Federal regulations for natural gas distribution and transmission pipelines, as well as for hazardous liquids pipelines.

Technically speaking: In accordance with pipeline safety regulations for oil pipelines, an operator’s integrity management program must include, at a minimum, the following elements:

  • a process for determining which pipeline segments could affect a High Consequence Area (HCA)
  • a Baseline Assessment Plan
  • a process for continual integrity assessment and evaluation
  • an analytical process that integrates all available information about pipeline integrity and the consequences of a failure
  • repair criteria to address issues identified by the integrity assessment method and data analysis (the rule provides minimum repair criteria for certain, higher risk, features identified through internal inspection)
  • a process to identify and evaluate preventive and mitigative measures to protect HCAs
  • methods to measure the integrity management program’s effectiveness
  • a process for review of integrity assessment results and data analysis by a qualified individual.

A 2013 assessment confirmed that the 55-mile-long segment of pipeline operating at 500 psi was experiencing internal corrosion. In recent years, the pipeline had been temporarily put out of service and repaired due to minor failures. Following the 2013 assessment, regulators determined that it would need to be replaced or brought back into compliance before it could be returned to service.

As the oil and gas company that owned the pipeline planned its future, they considered several alternatives. The first option considered was to permanently retire the pipeline, with the crude oil it carried transported by truck instead—an option that was both economically inefficient and more dangerous.

The second option was total replacement of the pipeline. However, the owner knew that new construction would be expensive due to the development that had taken place along the pipeline’s route in the decades following its original construction. It could take years to obtain the necessary permits, negotiate with homeowners, and tunnel under roads and highways before the first foot of new pipe could be laid.

The owner also explored a third option, the possibility of applying liquid epoxy coatings to the interior wall of the existing pipe, but feared the solution would not provide the desired longevity and safety factor sought for by the company.

The fourth option was to install a compressive-fit HDPE liner inside of the existing pipe. The corrosion-resistant barrier provided by an advanced polyethylene liner would extend the pipeline’s life by an additional 50 or more years, as well as provide dual containment, helping to improve pipeline environmental safety. Notwithstanding HDPE lined pipelines safety advantages and vastly improved longevity, this option was the best value, the entire rehabilitation could be accomplished for less than half the cost of pipeline replacement.

Nevertheless, HDPE liners had not been widely used as a method of achieving PHMSA compliance. Owners were concerned that regulations requiring periodic tests to measure wall thickness, a process that required tools to be send through the pipeline, was not practical with an HDPE liner. the oil and gas company decided to work with regulators to find an alternative approach to bring the pipeline back into compliance. In doing so, the company’s project team was successful in convincing regulators of the effectiveness of existing methods to test and assess HDPE lined pipelines, and that the dual containment provided by the system to be both a viable solution for extending pipeline life, and also meet PHMSA requirements and objectives.

3. DESIGN CHALLENGES

Finding an effective way to conduct pipeline assessments with an HDPE liner in place was just one of the challenges the oil and gas company and its project team would need to overcome on this project. Other major challenges included:

A long and winding route — During installation, the liner would need to negotiate over 400 separate bends along the pipeline’s nearly 56-mile route, many of which were particularly tight, short radius 45 to 90-degree bends.

Diverse urban, suburban and city landscapes — The pipeline segment began in the countryside 55 miles outside of Oklahoma City in a region that was dominated by dirt roads and farm fields at the time of its original construction 70-plus years ago. In the decades since the pipelines original construction, major developments have been constructed along the route, including towns, subdivisions and a golf course, busy highways and river crossings, and significant urban development around the pipelines termination near downtown Oklahoma City. Some segments of the line were buried as much as 20 feet beneath the surface. The construction team was challenged to work within the owner’s existing easement, minimizing disruption under this wide range of environmental conditions.

Record rainfall — The project was completed over an eight-month period between Oct 2014 and June 2015, which included one of the wettest springs in Oklahoma history. Record rainfall in May was accompanied by frequent tornadic activity. The excessive mud at many project sites, in combination with the heavy equipment involved in excavation and construction, resulted in deep mud and water-filled excavation sites, both of which slowed construction and limited the lining contractor’s access to the sites.

Compressive-Fit HDPE

Figure 1. Record spring rainfall created dangerous, muddy conditions for equipment and crews to work in.

4. THE LINER INSTALLATION PROCESS

The installation of the liner was completed in three phases, each of which included between 15 and 20 miles of pipeline. Before the lining process could begin, the line was first tested for strength and leaks using hydrostatic testing, a process that regulators agreed could replace the more typical approach to measuring wall thickness.

Each phase was further broken down into a series of installations ranging from just 25 to more than 3,000 feet in length. Working in coordination with the owner’s steel and excavation contractor, the HDPE lining contractor arranged for entry and termination sites to be excavated at the beginning and end of each installation.

In each case, the polyethylene pipe was delivered to site and fused together along the right of way. The fusion procedure involved setting two pieces of polyethylene pipe into a fusion machine in a straight line. After each piece was cleaned of any dust, dirt or other material, the two ends were trimmed and carefully aligned to allow for an exact flushness. The ends were then trimmed one more time before being brought together against a heating plate that had been inserted in the machine.

The ends remained under pressure until a visible bead formed completely around the pipe edges. At that point, the pressure is released, the fusion machine is opened and the heater plate is quickly removed. The two ends are then brought together and fused using pressure. After the fused pipe cools naturally, it is removed, the bead is trimmed and examined for any visible flaws.

Using compressed air, a blow down pig with a sizing plate was then inserted the entire length of the steel pipeline section to be lined. This allows the contractor to determine the presence of any abnormalities, such as pipe heavy wall changes, mitered welds, deep weld penetrations, ovallites and dents.

Fused sections of HDPE liner were then passed through a reduction roller box, temporarily reducing the size of the liner. The reduced liner was then pulled through the host pipe until the pull-head emerged at the other end. A wireline truck was used to measure tension and distance, allowing for a tight fit. After the sections were pulled in, time was allowed for the liner to “relax” and revert to near its original size.

When each of the three phases were complete, each segment again underwent hydrostatic testing before it could be returned to service.

Fused Sections of HDPE Liner

Figure 2. Fused sections of HDPE liner were passed through a reduction roller box, temporarily reducing the size of the liner, before being pulled through the host pipe.

5. CONSTRUCTION CHALLENGES

Crews had to adjust to a variety of conditions and environments during the eight-month construction period. In rural areas, they had to be careful to keep cattle from escaping through gates that were opened to gain access to installation sites. Later, when construction passed directly through a golf course where a tournament was underway, crew members were careful to site entry and exit points in the areas that were nondisruptive to the activities underway.

Similarly, when the pipeline traveled beneath a restaurant’s, car dealerships and residential neighborhoods and streets, the lining contractor choose pipe entry and exit points that were as far away from the structures and commercial activity as possible.

The pipeline also passed beneath railroad tracks and several major highways leading to downtown Oklahoma City. At river crossings, the pipeline varied from bury depths of 4 – 25+ feet deep. In other areas, excavations up to 20 feet deep were needed to reach the buried pipe.

The lining process itself was not always sequential. Because actual pipe construction sometimes deviated from the original plans, the project team had also to be prepared to address changes in wall thickness, pipeline abnormalities unexpected bends and other “surprises” along the way. In some cases, the pipe wasn’t constructed according to the original specifications, or contained an unmarked bend. Point repairs were also frequently needed. But the team persevered, never leaving the site until all three segments were complete. When a problem area emerged, the project team moved to a different section of the pipe while a solution for the problem area was developed. Crews typically installed multiple segments of pipe in a day. At the project highpoint, crews installed 90,000 feet of pipe in 30 days, completing two to three pulls a day.

6. RESULTS AND LESSONS LEARNED

In all, crews constructed and installed nearly 56 miles of 8-in-diameter internal HDPE pipe using the Compression Fit Liner system. Following completion, hydrostatic testing demonstrated that the new pipe was strong and leak- free, enabling it to be returned to service. Despite record rainfalls, harsh weather and muddy job sites that slowed construction and posed safety risks, the project was completed successfully in a high quality manner to the satisfaction of both the pipeline owner and PHMSA.

With minimal disruption to traffic, businesses and homeowners, the oil and gas company received a renewed reliable and durable pipeline internally protected against corrosion and abrasion, extending the existing asset’s life by 50 years or more. The new pipe-within-a-pipe also provides the oil company with a dual containment system for the oil it transports near farmlands, residences and businesses, offering peace of mind to the homeowners and others whose backyards and property the line passes.

Just as importantly, the project demonstrates to other owners of regulated pipelines that it is possible to meet PHMSA requirements by lining an aging pipeline with HDPE, with periodic inspections of wall thickness successfully accomplished using hydrostatic pressure testing.

END

THIS AWARD WINNING PAPER WAS PRESENTED AT NASTT’s 2016 N0-Dig ShowNASTT’s 2016 No-Dig Show

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June 2016, Unsolicited eMail
Outstanding project management and communication on the project, Excellent safety practices on site, Excellent quality of work preformed.
June 2015, Survey Monkey Respondent
Very good quality of work preformed, Would definitely recommend HEBNA!
June 2015, Survey Monkey Respondent
The weather is terrible but no one complained and continue to help in making progress on the project.
June 2015, Survey Monkey Respondent
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November 2015, Survey Monkey Respondent
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August 2015, Survey Monkey Respondent
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