Engineering & Construction Guide

Engineering & Construction Guide

Engineering & Construction Guide

Tite Liner® Engineering & Construction Guide

1.0 Introduction and Overview

United Pipeline Systems developed the Tite Liner® system in 1985. Since then, more than 13,000 km (8,000 mi) of pipelines have been lined. Installations of the Tite Liner® system have ranged from 50 mm to 1320 mm (2” to 52”) in diameter, with larger diameters possible.

The Tite Liner® system begins with a high-density polyethylene (HDPE) liner pipe with an outside diameter larger than the inside diameter of the steel pipe it will protect. The steel pipeline is sectioned to allow for the insertion of the HDPE liner pipe. Under normal conditions, average pull lengths are 600-800 meters. Longer pull lengths of a kilometer or more can be achieved depending on the diameter, bends, terrain and condition of the host steel pipe.

Next, a wireline cable is sent through a section of pipeline and attached to the liner pipe. The wireline pulls the liner pipe through United’s Roller Reduction Box, positioned at the insertion end of the pipeline section. The liner pipe is compressed radially as it passes through the Roller Reduction Box. This temporary reduction provides sufficient clearance between the steel pipe and the liner pipe to allow insertion. Until the pulling is complete, the liner is under tension, causing it to remain at a reduced diameter. When the tension is released, the liner pipe expands, creating a tight fit against the inner wall of the steel pipe.

Following relaxation of the liner pipe, the polyethylene flange-fittings are attached, and the line is ready for bolt-up and testing.

2.0 Design Considerations

The following information is required to enable the engineering of a Tite Liner® system installation:

2.1 Fluid composition2.2 Pipeline length2.3 Steel pipe outside diameter2.4 Steel pipe wall thickness2.5 Flange rating2.6 Type of joint (i.e., welded or mechanical)2.7 Operating temperature2.8 Operating pressure2.9 Test pressure2.10 Internal condition of line (e.g., scale build-up, etc.)2.11 System drawing (showing sidebends, overbends, fittings, etc.)2.12 Site location, right-of-way access and end point access

With this information and a possible site visit, United can determine project feasibility and provide a rough budget estimate for your project.

3.0 Materials and Fittings

The materials and fittings are designed to meet the specific requirements of each pipeline and can be separated into five categories:

3.1 Steel pipe materials3.2 Polyethylene liner pipe3.3 Flange connections3.4 Monitor system3.5 Lined fittings

1 Engineering & Construction Guide

Engineering & Construction Guide 2

3.1 Steel Pipe Materials

The steel pipe portion of a new installation is specified for the pressure and service requirements of the system.

3.2 Liner Pipe for use in the Tite Liner® System

High-density polyethylene (HDPE)

The polyethylene liner pipe is manufactured to United’s specifications by qualified polyethylene pipe manufacturers throughout the world. Typically, the HDPE liner pipe is extruded from PE 80 (PE 3408) or PE 100 (PE 4710) materials in accordance with ASTM specifications.

United selects and approves polyethylene manufacturers based on their reputations as leaders in the polyethylene pipe market. Approved manufacturers follow a stringent quality assurance program.

Note: United usually installs a customized thin wall liner to provide protection from corrosion, optimize installation lengths and minimize installation costs. A thicker polyethylene liner can be provided for more aggressive abrasive applications.

United Pipeline Systems can also offer other alternatives to HDPE for severe service such as sour gas and high temperature fluids outside the HDPE technical envelope. These more exotic thermoplastics typically withstand higher operating temperatures with a lower permeability than HDPE.

3.3 Flange Connections

All sections of steel lined with Tite Liner® pipe are joined using weld neck flange connections. These connections are capable of the ANSI pressure rating of the steel flanges. United uses

two types of flanged connections for the Tite Liner® system:

• Tite Liner® Flange Connection• Slurry Flange™ Connection

The seal for both of these connections is achieved by compression of the polyethylene flange-fitting between the faces of the steel flanges. All components of the connection should be specified and supplied as a unit. Specific information needed for this includes:

• Steel flange rating• Thread-o-let rating• Steel pipe outside diameter• Steel pipe wall thickness• Steel pipe and flange material specifications

3.3.1 Tite Liner® Flange Connection

The standard Tite Liner® flange connection is generally used in corrosive applications and is shown in Figure 1. This connection uses raised face weld neck flanges. Each steel flange is machined to match the inside diameter of the steel pipe and inspected to verify that the raised face dimension is correct. A radius that matches the radius of the polyethylene flange-fitting is machined on the inside of the raised face bore. A spacer ring is placed between each of the steel flanges to allow the correct amount of compression of the polyethylene flange-fitting. No gasket is required as the compressed polyethylene flange-fitting provides a pressure seal. The seal spacer ring provides long term stability to the connection. United manufactures the key components used in the connection to ensure the steel flange, the polyethylene flange-fitting and the steel spacer ring can be assembled as a unit. Quality control must be maintained in these items so that the:

• Steel flange internal bore matches the inside diameter of the steel pipe

• Radius of the steel flange internal bore matches the polyethylene flange-fitting• Raised face is square and of the correct diameter and tolerance to mate to the steel spacer ring• Spacer ring is manufactured to the correct width and diameter

The same connection is used to connect a lined section to an internally lined fitting or unlined connection. In these cases there will only be one polyethylene flange-fitting compressed between the two raised faces to achieve a seal. A special single-width spacer ring is used in this situation to provide the correct compression.

3.3.2 Slurry Flange™ Connection

For abrasive applications, United recommends the patented Slurry Flange™ connection shown in Figure 2. Both the steel flange and the polyethylene flange-fitting are machined with specially designed interlocking surfaces. When the two flanges are bolted together, a uniform surface is maintained across the interface, reducing or eliminating excessive wear from turbulence. The sealing method is the same as the standard flange connection. An optional gasket may be available to provide a secondary seal. The Slurry Flange™ connection incorporatesstandard bolting geometry to mate with standard flanges.

The Slurry Flange™ connection was designed and tested to meet ASME B31.11 of the Slurry Transportation Piping System Code.

3.4 Monitoring System

A unique benefit of the Tite Liner® system, a pipe-within-a-pipe solution, is the ability to monitor the performance of the system. Prior to liner insertion, thread-o-lets are welded to the steel pipe approximately 15 cm (6”) from each steel flange. United will drill a 3 mm (1/8”) hole through the steel pipe. At appropriate locations, a 12 mm (1/2”) riser pipe is connected to the thread-o-let and brought to surface. A valve is attached to this riser pipe above grade (see Figure 3). It is common practice to routinely operate this valve to ensure the integrity of the liner. All riser pipes can be supported with treated wood posts and protected on the surface by a guard fence.


3.5 Lined Fittings

The Tite Liner® system is best installed in long, straight sections. Standard fittings such as tees, short radius elbows and special configurations can be protected with factory- lined polyethylene or other suitable internal coatings. United can furnish special fittings internally lined with polyethylene to match the exact dimensions of the pipe sections.

4.0 Pipeline Preparation

4.1 New Pipeline

United can help to design and/or construct a new steel pipeline to facilitate economical liner pipe installation. With proper section lengths established before construction, flanges can be welded at end points and bends can be specified with acceptable radii. Proper welding techniques will ensure there is no excessive penetration to impede the insertion or damage the liner pipe. All internal weld bead penetrations should be kept to a maximum of 1.6 mm (1/16”) as shown in Figure 4.

4.2 Existing Pipeline

An existing steel pipeline will normally require more preparation than a new pipeline. A pressure test can be performed to ensure structural integrity of the pipeline. Depending on the service, an existing steel pipeline may require cleaning (see Section 5.2.1).

Fittings must be located and removed, after which a sizing pig is pulled through the line. The sizing pig will locate any obstructions such as protruding weld beads, dents, fittings or changes in wall thickness.

5.0 Tite Liner® System Installation

5.1 Site Preparation

5.1.1 Right-of-Way

When the Tite Liner® system is installed in new pipelines, the right-of-way is already cleared and all flanges are accessible. However, in rehabilitation of an existing buried line, provisions must be made to locate and access the line.

5.1.2 Excavation of Buried Line

At each end or mid-point, the line must be excavated to allow straight entry of the wireline cable and liner pipe. The figure below shows typical lengths and configurations of excavations. The length and width of the excavation required depends on numerous factors, including the line size and the depth of cover. United can provide project-specific excavation details and requirements once pertinent site information is obtained.

Sample midpoint bellhole detail


5.2 Line Preparation

5.2.1 Line Cleaning

Although cleaning is not usually required in a new line, an existing line may require cleaning once it is taken out of service prior to attaching steel flanges. Any significant hydrocarbon and/or corrosion scale products that would impede the insertion of the liner must be removed. Both the amount and type of hydrocarbon, corrosion or scale deposits must be considered. If cleaning is required, it can often be accomplished by the use of pigs and/or chemicals.

5.2.2 Liner Section Lengths

When a line is buried, excavations are made at each section end-point as described in Section 5.1.2. The steel line is cut at each excavation, and the flange connections are welded in place.

Installation segments are normally determined jointly by the owner/engineer and United. This is determined primarily by bends and other factors such as terrain, accessibility and pipe cleanliness, with care taken not to exceed achievable installation lengths.

Typical Average Pull Lengths

Liner SizeTypical Average Pull Lengths*

2” 400 meters

3” 500 meters

4” 600 meters

6” 700 meters

8” 800 meters

10” 800 meters

12” 800 meters

*Typical average pull lengths in straight, flat sections. Pull lengths can be longer or shorter depending on many factors, as discussed herein.

5.2.3 Removal of Tight Bends, Fittings, etc.

Fittings and excessive bends that prohibit the installation of the liner pipe must be removed and replaced with internally-lined flanged fittings or suitable replacement bends welded in place.

The ideal bend radius is approximately 50 pipe diameters (50D). A tighter bend radius can be utilized, although the length of the installation segment including the bend may be reduced.

5.2.4 Size Verification

Once end-points have been excavated, steel flanges installed and all known restrictionsremoved, the size of the line is verified to ensure no further restrictions exist.

The unobstructed bore of the steel pipe is established by passing a sizing pig through the steel pipeline. The sizing pig is made of steel and can break through rough weld tips or icicles. If it reaches a point that it cannot pass, the obstruction must be removed.

The following table shows sizing pig dimensions through 406.0 mm (16”).

Nominal O.D. of Steel Pipe

mm (inches)

Sizing Pig O.D. Amount Less Nominal Steel I.D.

mm (inches)

60.3 to 168.3 (2” to 6”) 5.08 (0.20)

219.1 to 323.8 (8” to 12”) 6.35 (0.25)

355.6 to 406.0 (14” to 16”) 7.62 (0.30)


5.2.5 Polyethylene Liner Installation

Polyethylene pipe used in the Tite Liner® system is manufactured to a custom diameter and wall thickness. Diameters of 4” or smaller may be delivered in coiled lengths up to 800 m (2500 ft) in length. Larger sizes are delivered in joint lengths up to 20 m (65 ft) and joined using the thermal fusion process.

The wireline cable is attached to a pig and sent through the section of steel pipe with compressed air. A pulling head is fused to one end of the polyethylene pipe and connected to the wireline cable. The polyethylene pipe is then pulled into the steel pipe through the United Roller Reduction Box.

5.2.6 Fusion Bead Removal

The external HDPE fusion bead is removed on all liners. The internal fusion bead may be removed for abrasive applications or for future pigging.

5.2.7 Polyethylene Flange-Fitting

Sufficient time for relaxation of the polyethylene pipe must be allowed before the polyethylene flange-fittings are attached. Once installed, the polyethylene flange-fitting provides a continuous lining in the steel pipe and onto the face of the steel flange.

5.2.8 Bolt-up & Pressure Test

After all lined sections are bolted together and a low pressure air test completed, the pipeline can then be pneumatically or hydrostatically tested and all flanged connections and thread-o-lets inspected for leaks.

5.2.9 Clean Up

Following bolt-up and testing, the monitoring riser pipes are attached to the thread-o-lets. The steel flanges are then externally coated, if required, and the line is ready for backfilling and service.


© 2008 Insituform Technologies, Inc.9/08

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Engineering & Construction Guide