# Pipe Joints

A pipe joint is adequately supported, for example, by a sand berm or a massive rig, and hit with a hammer at a specified impact energy.

## Incorrect Operations Index

W. Kent Muhlbauer, in Pipeline Risk Management Manual (Third Edition), 2004

### B3Joining (0–2 pts)

Pipe joints are sometimes seen as having a higher failure potential than the pipe itself. This is reasonable since joining normally occurs under uncontrolled field conditions. Highest points are awarded when high quality of workmanship is seen in all methods of joining pipe sections, and when welds were inspected by appropriate means (X-ray, ultrasound, dye penetrant, etc.) and all were brought into compliance with governing specifications. Where weld acceptance or rejection is determined by two inspectors, thereby reducing bias and error, assurances are best. Point values should be decreased for less than 100% weld inspection, questionable practices, or other uncertainties. Other joining methods (flanges, screwed connections, polyethylene fusion welds, etc.) are similarly scored based on the quality of the workmanship and the inspection technique.

100% inspection of all joints by industry-accepted practices warrants 2 points in this example.

URL: https://www.sciencedirect.com/science/article/pii/B9780750675796500091

## Pipeline systems

Maurice Stewart, in Surface Production Operations, 2016

### 11.5.1.4Stringing and bending

The steel pipe sections, or joints, in 40 or 80 ft. (12-24 m) lengths are trucked to the construction work area and strung out along the route in the areas where they are to be welded together (refer to Figure 11.26). Stringing is the delivery and aligning of the pipe joints along the side of the pipeline trench ready to be welded and tested before being lowered into the trench. Each joint of pipe has a specific place in the pipeline. The stringing crew ensures that each piece of pipe is placed where it belongs (refer to Figure 11.27). Inspectors check the pipe's designated numbers to ensure the joints are in the correct order (refer to Figure 11.28). The crew can unload 8 joints of pipe in under 10 min. The pipeline route is not straight nor is the terrain flat. The pipe must be bent to fit the ROW's topography. As necessary, the pipe joints are bent to follow the route of the pipeline and contours of the ground. A specialized pipe bending machine is used (refer to Figure 11.29). The amount of the bend in the pipe section is limited to avoid damaging the pipe or coating. Therefore, the pipeline must be bent in the field to fit the three-dimensional profile of the trench. Pipe joints must be bent prior to being welded.

URL: https://www.sciencedirect.com/science/article/pii/B9781856178082000110

## Process options and manual techniques for welding pipework fabrications

K R SPILLER, in Process Pipe and Tube Welding, 1991

### Vertical-up welding with basic electrodes

On pipe joints which require the root run to be of high quality it is customary to use basic cover electrodes with diameters of either 2.5 or 3.25mm. The 2.5mm diameter electrode is preferred as it results in the formation of a smaller weld pool which can be more easily controlled.

Once the arc has been established, the tip of the electrode is directed into the root gap and pointed at the weld pool. Extreme care is exercised at this stage to ensure that the arc does not ‘blow’ into the root gap. A short arc length is maintained throughout welding, since porosity will occur if the arc is too long. The welder can, if so desired, execute a V-shaped weave of the electrode tip, Fig. 1.3, the weave being made in a continuous smooth movement. In doing this the arc is brought out of the weld pool and up along the bevel face with a quick movement. The return movement is slowed sufficiently to allow just enough time for the weld pool to lose its fluidity, with the arc being returned to the weld pool and held for a short pause. This combined movement is then repeated up and along the other bevel face.

The practice of ‘whipping’ the tip of the electrode as used with rutile covered electrodes must be avoided to eliminate the occurrence of porosity and loss of control over the formation of the penetration bead profile. Another common practice – that of ‘hopping’ the electrode tip from one bevel to the other at the root of the joint – is also detrimental.

When stopping a weld bead which will be continued, care must be taken to ensure that the arc is not ‘broken off abruptly, otherwise a shrinkage cavity forms in the weld crater. Unless these are dressed and tapered by grinding it is unlikely that they will be completely remelted out when a restart is made. The recommended practice to avoid forming a crater is to ‘tail out’ the arc to the sidewall of the joint, then break the arc. The restarting technique requires a preheat to allow fusion and penetration to take place at the leading edge and underside of the crater. This is achieved by initiating the arc on the bevel face adjacent to the crater and the electrode angle of 80° to the vertical being altered to 110° for a few seconds so that ‘heat’ is passed over and under the crater.

URL: https://www.sciencedirect.com/science/article/pii/B978185573012050004X

## Mechanised arc welding process options for pipework fabrications

M G MURCH, in Process Pipe and Tube Welding, 1991

### TIG hot wire welding

The TIG hot wire process was developed in the mid 1960s4 as a method of achieving high metal deposition rates together with a weld integrity normally associated with conventional TIG welding. In its original conception the system used two power sources, a DC supply for arc current and an AC supply for resistance heating of the wire. The system produced minimal interaction between the arc current and the wire. The filler wire which is heated to near its melting temperature enters the weld pool behind the TIG arc.

More recently, a commercial hot wire system has become available employing a single DC power supply which shares its output between the arc and the resistance heated wire, as represented schematically in Fig. 2.7. The main advantages of this system are reduced capital equipment costs, small physical size (comparable with conventional TIG equipment) and ease of operation.

For circumferential pipe joints, the hot wire variant which operates in the continuous current mode is restricted to welding in the flat position on rotated pipe. It is used principally on pipe wall thicknesses greater than 6mm where a deposition level similar to that of MIG welding is beneficial. A typical example of a transverse section through a weld in 8mm thick wall Inconel 6251 pipe, which was welded in three passes, is shown in Fig. 2.8. In comparison, welding pipe of the same wall thickness with conventional TIG would require six passes.

URL: https://www.sciencedirect.com/science/article/pii/B9781855730120500051

## Corrosion Atlas

In Corrosion Atlas Case Studies, 2020

### Contributed By: Annelise Zeeman

#### Case History 09.11.04.001

 Material Unalloyed titaniumUNS R50400Welded joints (pipe seam weld and circumferential pipe to pipe weld) System High temperature acid piping in a chemical industry Part Longitudinal seam welded pipeNominal diameter 219.1 mmPipe thickness 3.8 mm Phenomenon Hydride formation and surface layer detachment Appearance Localized thinning in the welded regions Time in Service Several years Environment 94°C acid solution Cause Hydrogen generated at the high temperature corrosion enters in the material and creates a hydride layer that is brittle and detaches where the structure is coarse (the welded joints, longitudinal seam and pipe to pipe circumferential). The layer is uniform though the pipe internal surface but the coarse structure in the welded region favored the easy detachment Remedy Corrosion control Additional sentence case Materials Life Database
URL: https://www.sciencedirect.com/science/article/pii/B9780128187609000088

## JOINTS FOR PROCESS PIPING SYSTEMS

ByPETER SMITH, in Piping Materials Guide, 2005

### Material Compatibility.

The material used for the pipe joint must be mechanically and chemically compatible with the pipe transporting the fluid. If welding is required, then the two materials must also be chemically compatible to effect a correct weld. Further, the material of construction of the joint must have very close corrosion-resistant characteristics to the parent pipe, for the fluid transported internally and the external environment. For use in food and drug industries, the jointing material must not contaminate the process fluid.

Materials of differing chemical compositions can be welded together as long as there is no possibility of galvanic corrosion, the correct weld procedure is in place, and the weld is executed by a suitably qualified technician.

URL: https://www.sciencedirect.com/science/article/pii/B9780750677431500144

## Snubbing Theory and Calculations

Les Skinner PE, in Hydraulic Rig Technology and Operations, 2019

### Horizontal Hole Sections

Horizontal holes are like inclined straight holes, but the entire weight of the pipe is normal (perpendicular) to the centerline of the well. In other words, the deviation angle, α, is 90 degrees and sin α = 1.

From Eq. 4–20,

(4.21)${W}_{n}=\left({W}_{b}\right)\phantom{\rule{0.25em}{0ex}}$

Friction is calculated from Eq. (4.14) using the same friction coefficients found in Table 4.2.

#### Integral Joint Pipe

Friction when using integral-joint pipe becomes very significant since all the buoyed weight of the pipe acts downward and normal to the well's centerline. This becomes particularly important if the tubular has a heavy weight, like drill collars or heavy-walled tubing. The friction can become so great that it becomes impossible to push the BHA to the bottom of the hole.

#### Pipe With Upset Ends

This type of pipe is preferred for horizontal wells for several reasons. The upset connections support at least a portion of the buoyed pipe weight along its length. More of the pipe will be in contact with the wellbore wall due to additional sag above that seen in inclined wells because the weight normal to the pipe is greater. Friction is greater than inclined well segments but less than horizontal wells using flush-joint pipe (Fig. 4.8).

In open-hole work, there is a greater tendency for flush-joint pipe to become differentially stuck than with EUE jointed pipe. The pipe lays in a trough in the bottom of the wellbore created both by the curvature of the circular cross section of the hole and the deposition of a layer of filter cake in permeable well sections. The pipe may be turning under the influence of a hydraulic rotary table or power swivel. That rotation must cease each time a connection is made. It is at that point that the differential between the wellbore pressure and formation pressure acting across the filter-cake “seal” around the pipe can cause differential sticking.

In underbalanced flow-drilling operations, this may not be as significant an issue. Here, the differential is in the opposite direction, and differential sticking cannot occur. In other managed pressure operations where surface pressure held on the well replaces hydrostatic pressure from a mud column, differential sticking can still occur if the imposed overbalance is significant.

Hole cleaning becomes an issue in many drilling, recompletion, and workover operations involving horizontal hole segments. Cuttings, scale, and debris will settle to the bottom of the hole in most operations. Mud properties can be adjusted to suspend cuttings during connections, and the rotating pipe can help to stir up the cutting beds. During slide drilling (directional drilling without pipe rotation), the cutting beds simply build around the pipe if mud properties and flowrate cannot remove them.

Upset jointed pipe has the advantage in that the connections can be pulled or pushed down the hole, with or without rotation, to keep the cutting beds stirred up. This facilitates their removal by the mud that carries them out of the well.

Often, compression forces required to push the pipe to the bottom in any configuration well become so large that the pipe buckles. When the buckling becomes severe, there is additional friction added to the system from the unusual configuration of the pipe in the hole. More wall contact means more friction, so a knowledge of buckling is critical to understanding total friction acting on a pipe string.

URL: https://www.sciencedirect.com/science/article/pii/B978012817352700004X

## Pipeline Design and Construction

Don D. Ratnayaka, ... K. Michael Johnson, in Water Supply (Sixth Edition), 2009

### Steel Pipes

#### 15.12Steel Pipe Manufacture and Materials

BS 534 covers carbon steel pipes, joints and specials (bends and other fittings) but is partly replaced by BS EN 10224 (pipe ranging from 26.9 to 2743 mm outside diameter using steel of yield strengths 235, 275 and 355 N/mm2) and by BS EN 10311 for joints. BS EN 10312 covers stainless steel pipe. EN standards have been published and others are under development for polyethylene, galvanized, liquid epoxy and polyurethane coatings, mortar linings and external concrete and insulating coatings, but reference can be made to BS 534 for coatings and linings. BS EN 10224 uses pipe consistent with BS EN 10216-1, 10217-1 and 10220, but pipe to ISO 3183 (API 5L) and other standards can be used. CP 2010 Part 2 for design and construction of steel pipes on land remains current. BS EN 1295-1 covers structural design of buried pipelines for the water industry. Eurocode 3: BS EN 1993-4-3, issued in 2007, applies to design of steel pipelines which are not treated by other European standards covering particular applications; it can be used as soon as its national annex is published. This code requires consideration of 5 ultimate limit states, including fatigue, and three serviceability limit states including vibration. PD 8010-1 and -2 are intended primarily for oil and gas pipelines but apply to and provide useful design information for the water industry.

BS EN 10224 covers four principal welding methods for manufacture: butt (BW)—outside diameter up to 114.3 mm; electric (resistance) welded (EW)—outside diameter up to 610 mm; seamless (S)—outside diameter up to 711 mm and submerged arc welded (SAW)—outside diameter 168.3 to 2743 mm. In ISO 3183 the designations EW and SAW are recognized but seamless pipe is designated SMLS and LW means laser weld.

Steel pipes are fabricated from steel plate bent to a circular form or they may be continuously produced from a coil of steel strip bent to a spiral and butt welded along the spiral seam. Joints between coil ends of spiral welded pipes are known as skelp end welds. Butt welded pipes are made from rolled strip with a longitudinal seam furnace butt welded by a continuous process. Lengths of pipe are usually in the range of 9 to 12 m dependent on manufacture, transport and project requirements. Weld beads must be machined flush with the pipe surface at pipe ends to make them suitable for joint couplings. Spigot and socket ends, where shaped, are formed by die. Weld bead height needs to be limited for coating and lining. Electric (resistance) welding is done by passing electric current (by induction or direct contact) across the edges which are joined under pressure, without filler metal. Heat treatment at least of the weld zone is usual in sizes larger than DN 200. EW pipes now tend to be known as HFI (high frequency induction) pipes. Inspection typically includes chemical and mechanical material tests, ultrasonic inspection of plate and welds, radiography of welds and hydraulic pressure tests.

There are no standard classes for steel pipes: wall thickness above about DN 750 is designed for handling; internal pressure; buckling under external pressure and internal sub-atmospheric pressure; and to limit deflection when buried. External load carrying capacity in trunk mains is mostly a function of the backfill and compaction design. BS 534 sets out nominal wall thicknesses considered to be the minimum for handling and typical buried installations.

Steel grades as designated in ISO 3183 and, as from 2008, the American Petroleum Institute standard API 5L are designated by grade and by yield stress in thousands of psi, as Table 15.3. Grades less than grade B would not normally be used. Grades up to about X60 can normally be welded without special heat treatment. Their price is only marginally above that for grade B and provide good economy where high pressure or (typically for pipes above ground or installed underwater) significant longitudinal bending resistance is required.

Table 15.3. Steel grades to API 5L / ISO 3183

Grade A25 A B X42 X46 X52 X56 X60 X65 X70 X80
Yield strength psi 25 400 30 500 35 500 42 100 46 400 52 200 56 600 60 200 65 300 70 300 80 500
N/mm2 175 210 245 290 320 360 390 415 450 485 555

AWWA M11 gives a range of thicknesses and pressures and steels for diameters up to 4000 mm. Sizes in M11 are designated by outside diameter below 30 inches (762 mm), otherwise by inside diameter.

Pipe wall thickness, t (mm) for internal pressure is determined by hoop stress, as follows:

$t=\frac{PD}{2a\sigma e}$

where P is the internal pressure (N/mm2); D is the external diameter (mm); a is the design or safety factor; σ is the minimum yield stress (N/mm2); and e is the joint factor. The design factor, joint factor and definition of wall thickness depend on the design code. Design factors for hoop stress typically range from 0.4 to 0.8; the joint factor is 1.0 for SAW pipes and certain codes require the negative tolerance to be deducted from wall thickness. ASME codes B31.4 and B31.8 quote a basic design factor of 0.72 and state that this includes for thickness tolerance. For water supply under normal conditions, it is suggested here that the design factor of 0.5 (as given in AWWA M11 and the WRc pipes selection manual) is overly conservative and that, for high pressure long distance pipelines, a factor of 0.72 is realistic (after deducting thickness tolerance and any corrosion allowance) and up to 0.83 may be considered in some circumstances (PD 8010, BS EN 14183). For many water supply pipelines wall thickness is determined by handling and installation and the need to control deflection.

Further consideration can be given where particular conditions warrant: for example the American Society of Mechanical Engineers (ASME) code B31.8 quotes design factors for a variety of laying conditions. Where necessary the analysis can be elaborated to include ring bending, longitudinal bending, longitudinal stress from temperature changes, Poisson's ratio effects on buried (and thus restrained) pipe under hoop tension, combined (equivalent) stresses and where appropriate, for example for underwater pipes, can include strain based design.

BS EN 10224 and BS 534 give dimensions for common fittings, for example bends and branches. However, fittings can be made to any dimensions required, bends being made by cutting and welding together sections of pipe. For outside diameters up to 1016 mm, bends can be made by forming. Design of fittings and of any reinforcement needed is described in AWWA M11.

URL: https://www.sciencedirect.com/science/article/pii/B9780750668439000238

## Pipeline Design and Construction

Malcolm J. Brandt BSc, FICE, FCIWEM, MIWater, ... Don D. Ratnayaka BSc, DIC, MSc, FIChemE, FCIWEM, in Twort's Water Supply (Seventh Edition), 2017

### Steel Pipes

#### 17.17Steel Pipe Manufacture and Materials

BS 534 (for carbon steel pipes, joints and specials) is withdrawn but only partly replaced by BS EN 10224 (pipe ranging from 26.9 to 2743 mm OD using steel of yield strengths 235, 275 and 355 N/mm2) and by BS EN 10311 for joints. BS EN 10312 covers stainless steel pipe. BS EN 10224 uses pipe consistent with BS EN 10216-1, 10217-1 and 10220, but pipe to BS EN ISO 3183 (API 5L) and other standards can also be used. CP 2010 Part 2 for design and construction of steel pipes on land remains current. Eurocode 3: BS EN 1993-4-3 applies to the design of steel pipelines which are not adequately covered by other European standards covering particular applications. This code requires consideration of five ultimate limit states, including fatigue, and three serviceability limit states including vibration. BS PD 8010-1 and -2 are intended primarily for oil and gas pipelines but apply to and provide useful design information for steel pipes for water conveyance.

BS EN 10224 covers four principal welding methods for manufacture: butt (BW) – OD up to 114.3 mm; electric (resistance) welded (EW) – OD up to 610 mm; seamless (S) – OD up to 711 mm and submerged arc welded (SAW) – OD 168.3–2743 mm. In ISO 3183 the designations EW and SAW are recognized but seamless pipe is designated SMLS and LW means laser weld.

Steel pipes are fabricated from steel plate bent to a circular form or they may be continuously produced from a coil of steel strip bent to a spiral and butt welded along the spiral seam. Joints between coil ends of spiral welded pipes are known as skelp end welds. Butt welded pipes are made from rolled strip with a longitudinal seam furnace butt welded by a continuous process. Lengths of pipe are usually in the range of 9–12 m dependent on manufacture, transport and project requirements.

Weld beads must be machined flush with the pipe surface at pipe ends to make them suitable for joint couplings. Spigot and socket ends, where shaped, are formed by die. Weld bead height needs to be limited for coating and lining. Electric (resistance) welding is carried out by passing an electric current (by induction or direct contact) across the edges which are joined under pressure, without filler metal. Heat treatment at least of the weld zone is usual in sizes larger than DN 200. EW pipes now tend to be welded using the high frequency induction process which avoids electrode contact with the pipe. Inspection typically includes chemical and mechanical material tests, ultrasonic inspection of plate and welds, radiography of welds and hydraulic pressure tests. The need for stress relieving after welding is dictated by the thickness of plate or weld throat according to code; ASME B31.4 requires stress relieving for effective weld throat more than 32 mm.

Steel grades in ISO 3183 and, as from 2008, the American Petroleum Institute standard API 5L are designated by grade and by yield stress in thousands of psi, as Table 17.3. Grades less than grade B would not normally be used. API 5L covers two quality categories, PSL1 and PSL2, the latter requiring much tighter control on steel composition (Carbon Equivalent) and higher fracture toughness. PSL1 is commercially available up to grade X70, whereas PSL2 can be sourced up to X120. Selection of steel quality category and grade is usually on overall cost and, where operating conditions warrant, it is often beneficial to use as high a grade as possible. However, pressures in water supply pipelines usually vary considerably over their length. In parts of the pipeline subject to lower pressures minimum pipe wall thickness criteria (for handling and laying conditions) will govern. In such situations the proportion of the pipeline with thickness governed by internal pressure reduces as steel grade increases. Use of different grades in the same pipeline may be considered but adds to the site quality control difficulties of managing varying wall thickness.

Table 17.3. Steel grades to API 5L/ISO 3183

Grade A B X42 X46 X52 X56 X60 X65 X70
Yield strength psi 30 500 35 500 42 100 46 400 52 200 56 600 60 200 65 300 70 300
N/mm2 210 245 290 320 360 390 415 450 485
URL: https://www.sciencedirect.com/science/article/pii/B978008100025000017X

## Water supply and distribution systems

Alireza Bahadori PhD, in Essentials of Oil and Gas Utilities, 2016

### 8.18.3.1Force-locking pipe joints not actuated by longitudinal forces

Socket joints are usually force-locking pipe joints not actuated by longitudinal forces. When forming socket joints, care must be taken that the sealing rings seat accurately. In the case of bends, branches, and the like, forces must be deflected via abutments into the surrounding soil.

The nonmanipulative type of compression joint, as its name implies, does not require any working of the pipe end other than cutting square. The joint is made tight by means of a loose ring or sleeve that grips the outside wall of the pipe when the coupling nut is tightened. The manufacturer’s recommendations should be followed.