pop Hot tap REV 00

7/28/2019 pop Hot tap REV 00

1/31

1. TRABAJO MECANICO:

Paso 1 Se realiza la fabricacin del spool en nuestros talleres de CONTA Santa Cruz,compuesto de un niple de 4 con una brida WN de 600 lista para ser montado a un cao de 4u/o 8 pulg

Traslado del material con Personal y equipos para realizar la intervencin en el campo bajo lossiguientes actividades

Soldado del niple a cao a intervenir dando la ubicacin exacta en la lnea, una vez soldadorealizar la, verificacin de la soldadura con lquidos penetrantes o plaquetas de gammagrafa ydar el informe correspondiente una vez aprobado realizar el montaje de camisa de 4.

Montado de valvula de 4, Ubicacin de equipos y spool en el lugar demarcado para la

intervencin, Armado del spool a lnea a ser intervenida

Realizar el montaje de vlvula con sus respectivas empaquetaduras, posteriormente montar elcabezal de prueba para realizar la prueba hidrulica durante 4 hrs, para posteriormente recabarel informe correspondiente de aprobacin para luego montar el equipo centrado de hot tapdescrito


2/31

2. TRABAJO INTERVENCIONDE HOT TAP:

USO DE HOT TAPS PARA LAS CONEXIONES DE TUBERAS EN SERVICIO (Using Hot Tapsfor In Service Pipeline Connections)

Resumen gerencial:Las compaas de transmisin y distribucin de gas natural necesitan hacer conexiones a lastuberas muchas veces al ao para expandir o modificar sus sistemas existentes.Histricamente, esto ha requerido sacar de servicio una porcin el sistema y purgar el gas a laatmsfera para garantizar la seguridad al momento de hacer la conexin. Este procedimiento,llamado interrupcin e interconexin, causa emisiones de metano, prdida de producto yventas, molestias ocasionales a los consumidores y el costo de la evacuacin del sistema de latubera existente.Existe un procedimiento alternativo llamado hot tapping el cual realiza la conexin nueva detubera mientras la tubera permanece en servicio, con flujo de gas natural bajo presin. Elprocedimiento hot tapping consiste en adherir una conexin derivada y una vlvula a la parteexterna de una tubera en funcionamiento, y despus se corta la pared de la tubera dentrode la derivacin y se quita la seccin de pared a travs de la vlvula. El uso de hot taps evita

la prdida de producto, lasemisiones de metano y la interrupcin del servicio a losconsumidores.Aunque esta tcnica no es una prctica nueva, el mejoramiento reciente de diseo ha reducidolas complicaciones y la incertidumbre que los operadores experimentaban en el pasado. Variosparticipantes de transmisin y distribucin de Natural Gas STAR informan que usan losprocedimientos de hot tapping rutinariamente, los trabajos pequeos se realizan casidiariamente mientras que los ms grandes (ms de 12 pulgadas) se realizan dos o tres vecesal ao.Al realizar hot taps, los participantes de Natural Gas STAR han logrado reducciones deemisiones de metano y han aumentado los ingresos. Los ahorros de gas generalmente sonsuficiente razn para justificar el hacer todas las conexiones nuevas a las lneas en operacinmediante hot taps. El plazo de recuperacin de la inversin al usar hot taps con frecuencia esinmediato

2.1. Antecedentes tecnolgicos

En los sistemas de transmisin y distribucin de gas natural, con frecuencia esnecesario volver a colocar o expandir tuberas existentes, instalar vlvulas nuevas oreparar las viejas, instalar laterales nuevas, realizar el mantenimiento o tener acceso alneas durante emergencias. Histricamente, ha sido una prctica comn sacar deservicio una porcin del sistema durante la reparacin, ventilar el gas que contiene elsegmento aislado y purgar la tubera con gas inerte para garantizar la seguridaddurante la conexin.

Este procedimiento para realizar la interrupcin e interconexin difiere levemente

dependiendo de la presin del sistema. En sistemas de alta presin, las vlvulas quelos rodean se cierran para aislar el segmento de tubera y se colocan bloqueadoresadicionales (tapones insertados) junto a las vlvulas para evitar las fugas de gasnatural y mejorar las condiciones de seguridad en el lugar de la interconexin. En unsistema de baja presin, la longitud de la tubera que se sacar de servicio por logeneral es mucho ms corta. En lugar de cerrar las vlvulas que se encuentranalrededor, los tapones se usan para aislar la porcin de la tubera que estdirectamente en el rea de la derivacin. En ambos casos, el gas en el segmentoaisladode la tubera se ventila y la lnea se purga.

Los efectos relacionados con la interrupcin de la interconexin son tanto econmicoscomo al medio ambiente. El gas ventilado del segmento de tubera representa una

prdida de producto y un aumento de emisiones de metano. Adems, sacar de servicioun segmento de tubera puede en ocasiones causar interrupciones graves al servicio a


3/31

los consumidores. Por ejemplo, una conexin paralizada en una lnea de acero puederequerir de tres o ms das con la tubera fuera de servicio y la posible interrupcin delos embarques de gas natural adems de la liberacin de metano a la atmsfera.

La tcnica de hot tapping es una alternativa que permite que se haga la conexin sintener que sacar de servicio el sistema ni ventilar gas a la atmsfera. La tcnica de hot

tapping tambin se conoce como intervencin de la lnea, intervencin de la presin,corte de presin y corte lateral. El proceso implica adherir conexiones derivadas ycortar agujeros en la tubera en funcionamiento sin interrumpir el flujo del gas, y sinliberar ni perder producto. Los hot taps permiten nuevas derivaciones en los sistemasexistentes, la insercin de dispositivos en la corriente del flujo, desviacionespermanentes o temporales y es la fase preparatoria para el bloqueo de la lnea contapones de globo temporales inflables (tapones).

El equipo para realizar hot taps est disponible para casi cualquier tamao de tubera,materiales de tuberas y tasas de presin en los sistemas de transmisin y distribucin.El equipo principal para la aplicacin de hot taps tpicos incluye una mquina parataladrar, un accesorio de derivacin y una vlvula. El equipo de hot taps se describems adelante y se muestra en el Cuadro 1.

Mquina para taladrar. La mquina para taladrar generalmente consiste enuna barra giratoria o fija telescpica accionada mecnicamente que controla laherramienta de cortado. La herramienta de cortado se usa para producir unagujero piloto en la pared de la tubera para poder centrar una sierraperforadora que corta el cupn o la seccin curva de la pared de la tubera.

Accesorio. La conexin a la tubera existente se hace dentro de un accesorio,el cual puede ser un simple tubo corto soldado para una conexin pequea(por ejemplo, una pulgada) a una tubera ms grande, o una T de mangadividida de envoltura completa para brindar apoyo adicional cuando laderivacin sea del mismo tamao que la tubera principal. La T se envuelvecompletamente alrededor de la tubera, y cuando se suelda, ofrece el refuerzo

mecnico de la derivacin a la tubera portadora.

Vlvula. La vlvula de la conexin hot tap puede ser una vlvula de bloqueo ouna vlvula de control para una nueva conexin, y debe ser capaz de permitirque el cupn (la seccin de la pared de tubera cortada con una sierraperforadora) pueda quitarse despus de la operacin de cortado. Algunasvlvulas adecuadas incluyen las vlvulas de globo o compuerta, pero no lostapones ni las vlvulas de mariposa.


4/31

El Cuadro 2 ofrece un esquema general de un procedimiento de hot tap. Los pasosbsicos para realizar un hot tap son:

Conectar el accesorio a la tubera existente con soldadura (acero), pernos(hierro fundido) o adhesiones (plsticas) e instalar la vlvula.

Instalar la mquina de hot taps a travs de la vlvula permanente.

Llevar a cabo el hot tap cortando el cupn de la tubera a travs de la vlvulaabierta. Un dispositivo especial sostiene el cupn para quitarlo despus de laoperacin del hot tap. Sacar el cupn a travs de la vlvula y cerrar la vlvula.

Quitar la mquina de hot tap y aadir la tubera derivada. Purgar el oxgeno,abrir la vlvula y la conexin nueva estar en servicio.

VERIFICACION Y MONTADO DE EQUIPO DE HOT TAPS

VERIFICACION DE PRESION DE LINEA O EN SPOOL A INTERVENIR


5/31

INICION DE PERFORACION Y NIVELACION DE PRSERION EN PRUEBA:

Se realiz la verificacin de presiones en lnea (con la subida de presin a 2500 psi), luego deperforado se ve la nivelacin en ambos manometros la subida de presin que se nivelan enambos lados con una cada de presin muy pequea, luego se mantiene durante 2 horas paraque no varen y no exista cada alguna por fugas.

Los hot taps pueden ser verticales, horizontales o en cualquier ngulo alrededor de la tuberasiempre que exista espacio suficiente para instalar la vlvula, el accesorio y la mquina para

hacer el hot tap. La tecnologa actual permite que las derivaciones se hagan en todo tipo detubera, a todas las presiones, los dimetros y las composiciones, incluso en tuberas viejasque se fusionan a una nueva. Ahora se encuentran disponibles mquinas para realizar hot tapsnuevas de peso ligero que permiten realizar el trabajo con un solo operador, sin bloqueo nireforzamiento adicional.

Los manuales de seguridad y las directrices de procedimiento estn disponibles a travs delAmerican Petroleum Institute (API), American Society of Mechanical Engineers (ASME) y otrasorganizaciones para el soldado en tuberas en servicio de todos tamaos, tasas de flujo yubicaciones. Esos manuales ofrecen informacin sobre qu considerar cuando se suelda,incluyendo la prevencin de aberturas por quemadura, el flujo en las lneas, el grosor del metal,los accesorios, el tratamiento de calor posterior al soldado, la temperatura del metal, laconexin hot tap y el diseo de la soldadura, y el contenido de la tubera y el equipo.


6/31

Los catlogos de equipo y los manuales del vendedor tambin son buenas fuentes paradeterminar qu tamao y tipo de equipo es el ms apropiado. Varios vendedores han publicadodirectrices globales y guas para realizar los procedimientos hot tap, incluyendo la informacinpara la derivacin en varios materiales, la evaluacin y la preparacin del lugar de trabajo, laseleccin y la instalacin de accesorios y otro equipo, y las precauciones de seguridad. Lo msimportante, debido a que este procedimiento es peligroso, cada hot tap potencial debe

evaluarse individualmente y debe prepararse o revisarse un procedimiento detallado y porescrito antes de comenzar cada trabajo para garantizar que se sigan todos los pasoscorrectamente y de manera segura.

2.2. Beneficios econmicos y para el medio ambiente

Los beneficios clave econmicos y al medio ambiente al emplear los procedimientos dehot taps en lugar de conexiones con tubera fuera de servicio incluyen:

La operacin continua del sistema se evita sacar de servicio la tubera y lasinterrupciones.

No se libera gas a la atmsfera. Se evitan los cortes, la realineacin y volver a soldar las secciones de tubera. La reduccin del costo relacionado con la planificacin y la coordinacin, reuniones,

programas, documentacin, produccin perdida y mano de obra directa. Seguridad mejorada para los trabajadores. Eliminacin de la obligacin de notificar a los consumidores de gas sobre las

interrupciones de servicio.

Al garantizar que se sigan las mejores prcticas cuando se realiza un hot tap, se reduce eltiempo necesario para realizar el procedimiento as como el potencial de que falle.

Los operadores pueden evaluar los aspectos econmicos de realizar el hot tap comoalternativa a la conexin con la suspensin del servicio siguiendo los cinco pasossiguientes:

Paso 1: Determinar las condiciones fsicas de la lnea existente. En preparacin pararealizar un proyecto de hot tap, los operadores necesitarn determinar la presin mximade operacin (durante la realizacin del hot tap), el tipo de material de la tubera (acero,hierro fundido, plstico) y la condicin de la tubera principal (corrosin interna y externa,grosor de la pared) para garantizar la seguridad del proyecto. Una conexin de hot tappuede hacerse en una tubera solamente cuando el material de la tubera principal est enbuenas condiciones. Otras condiciones que deben evaluarse incluyen la ubicacin devlvulas cercanas de aislamiento deemergencia para casos en los que ocurra un accidente, el dimetro deseado de laderivacin, el espacio de trabajo alrededor de la conexin, la ubicacin de otrassoldaduras de la tubera y las imperfecciones u obstrucciones.Los operadores tambin deben determinar si la lnea est en circuito, ya que muchas

compaas de transmisin prefieren evitar perturbaciones de funcionamiento cambiando lacarga a una lnea paralela. Se recomienda que se prepare y siga un plan por escrito paragarantizar la evaluacin completa y adecuada de una conexin futura.

Paso 2: Calcular el costo de realizar la interrupcin e interconexin. El costo de unproyecto real incluir los costos directos como los materiales y el equipo, los requisitos desoldadura, el control de calidad, los costos de purgado, la mano de obra y los gastos deprogramacin. Algunos gastos indirectos adicionales o costos ocultos pueden incluir elcosto de las vlvulas de cerrado, la publicidad de qu servicio se interrumpir,reencendido del servicio de los consumidores, y las excavaciones y los tapones y lasconexiones de purga. Se recomienda a los operadores que consulten los datos histricospara determinar estos costos.

Para fines del alcance de este anlisis, los costos de materiales y mano de obra paracortar la seccin de la lnea y soldarla en una conexin en T con el mtodo de sacado de


7/31

servicio de la tubera se suponen que son comparables al costo de soldar el accesorio yrealizar un hot tap cuando la conexin de derivacin sea del mismo tamao que la tubera.Sin embargo, el costo de la prdida de gas mediante la ventilacin y el purgado del gasinerte son nicos para el mtodo de interrupcin e interconexin.Las frmulas usadas para determinar el costo del mtodo de interrupcin e interconexinse muestran en el Cuadro 3. Para estos clculos, la presin baja se define como menor de

2 psig.

Para fines comparativos, el clculo del costo del mtodo de interrupcin e interconexindebe tomar en cuenta un panorama con mltiples proyectos. Esta perspectiva deproyectos mltiples permite un anlisis comparativo ms completo dados los costos decapital iniciales de ser propietario y operar una mquina de hot taps y la necesidad derealizar varias interconexiones durante un ao dado. Cmo los clculos de costo puedenaplicarse a un panorama de conexiones mltiples. La situacin hipottica presentadaincluye varios proyectos en tuberas de varios tamaos y presiones. Sin embargo, losclculos de costo, solamente se ofrecen en el caso de una tubera de 4 pulgadas y slocubre los costos directos.

Hot Tap and Line Stops

A guide for those who know very little, but who may

have a need to know


8/31

By: Lindsey Lee PE, Principal Engineer, FLOWSERVE Industrial Services, 6330

Dixie Drive, Houston TX, 713-844-7656

Hot Taps and Line Stops are under pressure drilling operations, meaning that a

pipe or other pressure vessel is drilled into, while the system remains in service, and

under pressure. There are many reasons to do this, and by the same token, there aremany good reasons to not do this, if a system can be shut down, in order to perform the

drilling operation. A good example of a need to perform a hot tap, is to connect a

service (for example a new homeowner needs water service connected to a system

serving many others). Other people would be inconvenienced if the system were to be

shut down, depressurized, connected, sanitized?, brought back online, all to connect one

service. For this reason, it is very common to perform a hot tap. (A hot tap is

commonly assumed to mean drilling into a pipe that is live, it may, or may not actually

be hot).

This paper was written as an aid, to those technical persons, who know little or nothing

about hot taps and line stops. There are quite a few different publications, technicalarticles, manuals, and other printed matter that delve into the details of various aspects

of hot taps and line stops, this short paper is intended to simply hit the high spots.

Part I, Why go to all of this trouble?

It is really a lot of trouble to perform a hot tap, or a line stop, but these operations

provide us a tool to be used, to avoid shutting down a pipe system. In order to shut

down a pipe system, it may be necessary to depressurize, purge, clean, inert etc. To

bring the system back up, may take just as much work. For example, in an industrial

process unit, shutting the unit down might take days, or longer, result in hundreds of

thousands of dollars in lost production, and would impact other operations in the

facility. For this reason, continuous operating systems, such as chemical process units,

refineries, power plants, etc., shut down very rarely, for them, a hot tap, or line stop, is

the only economical option. By the same token, if a city water system is shut down, as

it loses pressure, contaminants could enter the system from groundwater, therefore,

municipal water systems are also on and pressurized 24/7. In all of these cases, it is

very desirable to remain in service, under pressure, and operating.

Please note, Hot tapping and line stopping are both science, and art, the state of the

industry is such, that there are as many unanswered questions, and items to still be

determined, as there are hard fast answers. For example, at 1 ft/second, flow velocity,the coupon (section of pipe that is cut out), will generally not be pulled off of the pilot

bit, with u-wires, to retain it. On the other hand, at 1000 ft/second, nothing that is

currently available in the industry, would keep the coupon (or pilot bit for that matter),

in place. For this reason, often the client will ask, is this flowrate too high, or can I go

higher. There are also higher pressures, larger sizes, and many other areas to be

developed in the art, sizes greater than 48 diameter for line stops, and 72 diameter for

hot taps, become very rare, FLOWSERVE recently completed a line stop on a 60 water

line in Columbia South America, at 150 psi, really stretched the limit on the available

head, and the supporting equipment.

Hot taps and line stops involve the use of specialized equipment and highly trainedtechnicians, in order to cut a hole in a pipe, without taking the pipe out of service, or


9/31

lowering the pressure. This is most often done in Chemical Plants, Refineries, Power

Plants, Manufacturing Plants, Nuclear Power Plants, or any other location, where loss of

service, is not acceptable. This technical paper is intended to be a primer of the hot tap

and line stop operation, primarily intended for those who have little if any prior

knowledge of the process. This work is highly technical, requires years of training,

highly specialized equipment, and should not be attempted without proper training andinstruction.

Part II, What is a hot tap.

A hot tap in its simplest form, involves drilling or cutting a hole in an existing pipe,

while the pipe is under pressure, and at operating temperature. For the reasons

discussed above, someone wants to establish a new service to an existing pipe, it is not

convenient or practical to take the system out of service, therefore a hot tap is required.

For example, a process plant may use high temperature steam, as an integral part of its

process. Shutting the steam line down might involve shutting one or more production

units down, which could involve hours, days, or weeks of lost production, plus aconsiderable cost to bring the unit back up. The hot tap is performed, through the

clients valve, the valve is closed, the hot tap machine is removed, then the client/owner

hooks up to his new service connection.

The Coupon, is the section of pipe that is removed, to establish service. It is very

highly desirable to retain the coupon, and remove it from the pipe, and in the vast

majority of hot taps, this is the case. Please note, short of not performing the hot tap,

there is no way to absolutely guarantee that the coupon will not be dropped, but we

can do a great deal to make this a very rare occurrence. Coupon retention is mostly the

job of the u-wires, these are wires which run through the pilot bit, and are cut and

bent, so that they can fold back against the bit, into a relief area milled into the bit, and

then fold out, when the pilot bit has cut through the pipe, in almost all cases, multiple u-

wires are used, to act as insurance against losing the coupon, if the u-wires are in good

condition, this normally works very well, the coupon is brought out, everything is fine.

Here are some of the factors, which adversely affect coupon retention;

High Flowrate (can include both liquids and gases)

Viscous fluids

Bad U-wires

Dirty pilot bit, such that the u-wires are not free to rotate out

Pulling back out, after the pilot bit has passed through the cut (this has been

done before, if a technician did not complete the cut, he pulls back, shearing off

the u-wires, then runs the machine back down to complete the cut, with broken

u-wires!).

Simply keep in mind, that no matter how hard we try, it is still possible to

lose, or drop the coupon into the pipe, that is one of the inherent risks in hot

tap and line stop operations. If it is not possible to risk losing a coupon, an

alternative to hot tapping should be considered!


10/31

Part III, How do we perform a hot tap?

A. Hot Tap Setup

For a simple hot tap, there are three major components necessary to safely tap into a

pipe, the fitting, the valve, and the hot tap machine (which includes the cutter, andhousing). The fitting is attached to the pipe, normally by welding. In many cases, the

fitting is a full encirclement split tee, with a flanged outlet (See Figure 6). Onto this

fitting, a valve is attached, and the hot tap machine is attached to the valve (see

FIGURE 1). For hot taps, new studs, nuts, and a new valve should always be used, as

the studs, nuts, and valve will become part of the permanent facilities and equipment.

The fitting/valve combination, is attached to the pipe, and is normally pressure tested by

the site owner. The pressure test is very important, so as to make sure that there are no

structural problems with the fitting, and so that there are no leaks in the welds (it makes

no sense to cut a hole in a perfectly good pipe, and to create a new leak in the

system).

The hot tap cutter, is a specialized type of hole saw, with a pilot bit in the middle,

mounted inside of a hot tap adapter housing. The hot tap cutter is attached to a cutter

holder, with the pilot bit, and is attached to the working end of the hot tap machine, so

that it fits into the inside of the tapping adapter. The tapping adapter will contain the

pressure of the pipe system, while the pipe is being cut, it houses the cutter, and cutter

holder, and bolts to the valve.

Key Points Hot Taps:

Client/Owner supplied valve

Primarily to establish new service

Can be size on size, or smaller hole cut into larger pipe

New studs and nuts should be used to bolt on the valve, as it becomes part of the

permanent installation


11/31

Figure 1, Hot Tap Stackup

B. Hot Tap Operation

The Hot Tap is made in one continuous process, the machine is started, and the cut

continues, until the cutter passes through the pipe wall, resulting in the removal of a

section of pipe, known as the coupon. The coupon is normally retained on one or more

u-wires, which are attached to the pilot bit. Once the cutter has cut through the pipe, the


12/31


13/31

FIGURE 2 - Valve, Pivot Head, Line Stop Housing and Line Stop Actuator

Stackup


14/31

B. Line Stop Operation

A Line Stop starts out the same way as does a Hot Tap, but a larger cutter is used,. Thelarger hole in the pipe, allows the line stop head to fit into the pipe. Once the cut is

made, the valve is closed the hot tap machine is removed from the line, and a line stop

actuator is bolted into place. New gaskets are always to be used for every setup, but

used studs and nuts are often used, because this operation is a temporary operation,

the valve, machine, and actuator are removed at the end of the job. New studs, nuts, and

gaskets should be used on the final completion, when a blind flange is installed outside

of the completion plug. The line stop actuator is operated, to push the plugging head

(line stop head), down, into the pipe, the common pivot head, will pivot in the direction

of the flow, and form a stop, thus stopping the flow in the pipe.

C. Completion Plug

In order to remove the valve used for line stop operations, a completion plug is set into

the line stop fitting flange (Completion Flange). There are several different types of

completion flange/plug sets, but they all operate in basically the same manner, the

completion plug and flange are manufactured, so as to allow the flange, to accept and

lock into place, a completion plug. This completion plug is set below the valve, once

set, pressure above the plug can be bled off, and the valve can then be removed.

Figure 3 Completion Plug, attached to boring bar, with ball check valve, and plugholder

Once the plug has been properly positioned, it is locked into place with the lock ring

segments, this prevents plug movement, with the o-ring becoming the primary seal.

Several different types of completion plugs have been developed with metal to metal

seals, in addition to the o-ring seal.


15/31

Figure 4, completion plug in place, boring bar is released and retracted, the tapping

machine can now be removed, as can the valve and holder, leaving a plug ready to be

blinded to complete the job.

Key Points Line Stops:

Service Company supplied (rental) valve

Primarily to stop flow in the pipe

Higher pressure pivot head operations must be size on size, for lower pressure

applications, a folding head may be used, subject to pressure and service

limitations.

Should use new studs and nuts to bolt on blind flange, may want bleeder on

blind flange.

Part V Safety considerations Job Planning

In almost all situations, basic hot tap and lines stop operations involve cutting a hole in

a pipe, or other pressure vessel, which is at operating temperature and pressure.

There are two significant and quite different job planning operations, both must

be completed prior to starting the hot tap. The first planning operation, is often

part of a Job Safety Analysis (JSA), which should include the site owner, his

technical personnel, and the service company selected to perform the work. This

process must include all applicable safety considerations, including but not


16/31

limited to pressures, temperatures, pipe/tank contents, safety, and environmental

issues (are special arrangements necessary for pressure bleed off, for example

oil/gasoline verses steam or water). Once the JSA is completed (prior to putting

the fitting on the line, or mobilizing equipment), the decision to go ahead with

the job is made.

When the job is definitely a go, a fitting is welded onto the pipe,equipment/personnel are mobilized to the site, then it is time for the second job

planning operation, normally starting with a safety discussion. The job should

then be planned out as to who will do what, and when. The job calculations are

also completed at this time, for example, the travel necessary to complete the

cutout of the coupon, and not drill through the backside of the pipe (drilling

through the opposite side of the pipe, can result in a complete shutdown of the

unit, explosions, fire, injuries, even including fatalities, so this possibility should

never be discounted!).

Part VI. Hot Tap and Line Stop Cutters

For small holes in pipes, a common drill bit is commonly used, (up to nominal two inch

diameter holes). For sizes above one inch, hot tap and line stop cutters are essentially

specialized hole saws. The hole saw is held in line for the cut, by a pilot bit (modified

twist drill bit, or specialized pilot bit). The pilot bit also normally has one or more u-

wires, which are set in the bit, and go in, but do not come out, so as to retain the

coupon on the cutter/pilot bit assembly. Figure 3 is a small cutter setup, Figure 4 is a

larger cutter pilot setup for larger machines.

Figure 3, Cutter holder & pilot bit, & assy, small setup (FLOWSERVE/IPSCO

IP-100)


17/31

Figure 4, cutter, holder, and pilot for a large machine, (FLOWSERVE/IPSCO IP

914), illustrating holder, cutter, pilot bit with u-wires, and socket head cap screw bolts

and lock-nuts.

Variations in cutters include carbide or tool steel cutter teeth, the design/profile of the

teeth, pass-through holes in the cutter barrel, number of teeth, and the overall geometryof the cutter holder connection points. Cutters used to cut through tanks, or blind

flanges have significantly less teeth, than cutters used for conventional hot taps/line

stops.

In order to understand how pipe cutters are designed, and to understand their sizes, it is

important to review pipe sizes, what is referred to here, as nominal, and actual cutter

dimensions.

Nominal sizes refer to the approximate inside diameter of the pipe, for example, a 2

(nominal) pipe has an outside diameter of 2.375 (2 3/8), with the most common size or

schedule (schedule 40), having a 0.154 wall thickness, with an ID of 2.067. Thinnerpipe (lower schedule number) has a larger ID, thicker pipe (higher schedule number),

has a smaller pipe ID. Since a line stop head must enter the pipe, and since the head

must pivot and then seal, a line stop cutter is normally a larger OD cutter than is a hot

tap cutter, on smaller sizes (up to nominal 16 inch), there are actually two different sizes

of cutter, the smaller OD cutter is the hot tap cutter, the larger OD cutter is the line stop

cutter. Line stop valves must also have a larger ID, and be full port, since the cutter has

to be able to pass through the valve. For hot tapping, there should be a minimum of1/8

diameter difference between the full port ID of the valve, and the OD of the cutter, so as

to not jam a cutter as it advances through the valve.


18/31

Table 1, common sizes of hot tap, and line stop

cutters

Figure 5, cutout detail of a hot-tap/linestop cutter going through the pipe

Part VII Fitting Selection and design considerations

Pipe

HT

Cutter LS Cutter

OD OD OD

3 1/2 2.438

4 1/2 3.438 3.938

6 5/8 5.469 5.938

8 5/8 7.312 7.875

10 3/4 9.500 9.875

12 3/4 11.500 11.812

14 12.750 13.062

16 14.688 15.062

18 15.062 17.000

20 17.000 19.000

22 19.000 21.000

24 21.000 23.000

26 23.000 25.000

28 25.000 27.000

30 27.000 29.000

32 29.000 31.000

34 31.000 33.000

36 33.000 35.000


19/31

There are many different considerations on selecting hot tap and line stop fittings, the

simplest form of a hot tap fitting, is a simple flanged nozzle, which is welded to the

pipe. Keep in mind that there are serious engineering considerations as to what should

be put onto the pipe, for example, even a simple small hot tap on a large pipe (cutting a

two (2) inch hole in a twelve (12) inch line for example), removes some of the run pipe,

resulting in a loss of cross sectional area, plus adding stress concentrations to theequation. It is always necessary to perform an engineering evaluation of the system, so

as to determine the correct type of fitting, so as to prevent pipe failure, during, or after

the cut. As a minimum, an area replacement calculation should be run, in accordance

with applicable code standards, so as to assure that the pipe is sufficiently reinforced by

the fitting, prior to cutting a hole in the pipe. Common weld-o-lets, are sized, so as to

provide enough material, so that allowable pipe stresses are not exceeded as a result of

the hot tap. For many applications, it is necessary to use a full encirclement fitting, such

as is illustrated in Figure 6.

Figure 6, Typical Full Encirclement Hot Tap Fitting, with flange.

In most cases, the fitting is welded onto the pipe in the location desired for the new

service. The ends of the fitting are welded to the pipe, the run seam is also welded

together, the inside of the hot tap nozzle is never welded, as this would result in severe

cutter damage, an unsuccessful cut, and a very dangerous situation. Weld material isusually stronger and harder than the base material, a cutter would be seriously damaged,


20/31

were the area to be backwelded, prior to making the tap (backwelding refers to

welding a bead inside the nozzle part of the fitting, right where the cut is to be made,

backwelding will often destroy a hot tap cutter!).

A full encirclement fitting will do a couple of things that a simple nozzle will not, it will

assist to re-round thin-walled pipe, that may not be round, it will handle the horizontalstresses that the line stop head will place on the pipe, it will also handle the bending

stresses applied by the line stop head. For all of these reasons, it is generally much

safer, to use a full encirclement fitting on hot tap and line stop operations.

Hot Tap and Line Stop Fitting Design Codes for Hot Tap Fitting Designs

ASME B 31.1 for Power Piping, is primarily for power plant design, fittings are tested

to 1.5 times design pressure

ASME B 31.3 for Process Piping, is primarily for chemical plants, refineries etc.

ASME B 31.4 is for liquid pipelines, for transportation of fluids

ASME B 31.8 is for gas transmission, and distribution systems.

This paper will not go into a great deal of information about design code specifics,

other than to mention that the design of the fitting(s) must comply with the applicable

design code.

Part VIII Odd Jobs

The following are different types of jobs, all can be done, all have been done, but all

require specialized equipment, procedures, and planning.

Across the line stop is a method of cutting a hole in the pipe, and inserting a plugging

head directly in the line, so as to stop the flow into a stub-out or nozzle directly below

the hot tap cut. For example, to change out a valve on a drain on the bottom of the pipe,

a nozzle or weld o let is installed on the top of the pipe, a hot tap is made through the

valve, a special head is lowered and seals against the opposite pipe wall, allowing for

removal of the drain valve

Angle Taps, are hot taps made at an angle different from 90 degrees to the flowdirection of the pipe. On all angle taps, the cutter is often much longer than on

conventional taps, and an angle tap boss is normally used, to allow the pilot bit to drill

directly into the pipe at 90 degrees, so as to prevent damage to the pilot bit, housings,

valve, and pipe, resulting from the side loads placed on the bit, but the angled pipe.

Bag Stop is a process, whereby a small hot tap is made into a pipe, and an inflatable

pipe plug is inserted into the pipe, so as to allow the plug to stop the flow in the pipe.

This system is a bit risky, and is limited to very low pressure applications, limited by

the pressure limit of the inflatable plug, small diameter systems up to about 75 psi max,

larger ones, are limited to single digit pressures (under 10 psi).


21/31

Elbow Taps and Stops are taps, and sometimes line stops, done through a pipe

elbow. This is only done, if it is not possible to use a straight run of pipe, as it requires

a special type of fitting, and a specially modified cutter.

High Temperature and/or High Pressure Stops are any hot tap, or line stop with

pressure temperature combinations that would exceed the standard ANSI Class 600 pipesystems, or any temperature of the system exceeding 400 degrees F. There are many

different methods of stopping flow in high temperature and/or high pressure

applications, but the normal pivot heads for line stops, and stock hot tap machines, are

not rated to these pressures, so specialized equipment is used here.

Permanent Stop is a process of using a modified line stop head, or FLOWSERVEs

Perma-Stop system, to permanently seal off the end of the pipe, for example, if a client

wants to abandon a section of pipe, a fitting is welded onto the pipe, and a permanent

plug is placed in the line, allowing the pipe downstream of the plug to be cut off, and

abandoned.

Part IX Conclusions

The purpose of this paper, is to offer an insight into the area of hot taps and line stops.

This paper is not intended to address all possible engineering issues with hot taps and

line stops, rather, it is intended to provide a basis for discussion of the most important

considerations of hot taps and line stops. The paper should serve as a starting point in

an engineers education as to the many facets of hot taps, line stops, and other similar

and related under pressure operations. Service companies who routinely perform hot

taps and line stops, are a good source of information about these operations, they should

be brought in early, to discuss feasibility of a particular operation, estimated costs, and

design considerations associated with the proposed operation.

Bigraphical;

Lindsey Lee PE

I am Operations Manager, and Principal Engineer for FLOWSERVE Online

Services, Houston TX. This is an industrial Services Company, does hot taps,

line stops, onstream leak repair, concrete repair, field machining, and other

specialty service work. FLOWSERVE/IPSCO also manufactures and sells

hot tap and line stop fittings, and a complete line of equipment. At thislocation, I oversee much of the project engineering, equipment modification,

and fitting design, as well as supervise the crews locally who do the work. I

started my professional career with Halliburton, worked for both Halliburton

Services, and the Brown & Root side of the company, as well as several other

service companies prior to joining FLOWSERVE two years ago. I have acouple of patents from my Halliburton days, several published articles, I

write/edit operations manuals, job procedures, and technical documentsdealing with this work. I am a licensed mechanical engineer, based in

Houston TX


22/31

DescripcinSimbologa Dato Unid

A53/A 106B S 15000 Lb/Pulg2

Temp. -20oF 650oF

Ef. Tubo SinCost. E 1

Diam. Int. Tubo D

Tubo de 6" Diam.ext. Esp D

6,625 0,28 6,065 ESPESOR Diferencia

PRESION

Presion t t P

Lb/Pulg2 Pulg mm pulg mm mmLb/Pulg2

1440 0,31 7,85 1/46,3

5 0,001300,9

5

1340 0,29 7,27 7/325,5

6 0,791130,9

81240 0,26 6,70 3/16 4,7 1,59 963,18

P


23/31

6

1140 0,24 6,13 5/323,9

7 2,38 797,53

1040 0,22 5,57 1/83,1

8 3,18 633,98

940 0,20 5,02 3/32

2,3

8 3,97 472,49

840 0,18 4,46 1/161,5

9 4,76 313,02

740 0,15 3,92 1/320,7

9 5,56 155,54

640 0,13 3,37

A53/A 106B S 14350 Lb/Pulg2 tDiferenc

ia P

Temp. -20oF 700oF pulg mm mmLb/Pulg2

Ef. Tubo SinCost. Et 0,9566 1/4

6,35 0,00

1190,56

Diam. Int. Tubo D 7/325,5

6 0,791035,0

1

Tubo de 6" De Esp D 3/164,7

6 1,59 881,46

6,625 0,28 6,065 5/323,9

7 2,38 729,86

1/83,1

8 3,18 580,19

3/322,3

8 3,97 432,40

1/161,5

9 4,76 286,46

1/32 0,79 5,56 142,34


ia P

Temp. -20oF 750oF pulg mm mmLb/Pulg2

Ef. Tubo SinCost. Et 0,8633 1/4

6,35 0,00 969,62


6 0,79 842,94


6 1,59 717,88

6,625 0,28 6,065 5/32

3,9

7 2,38 594,41

1/83,1

8 3,18 472,52

3/322,3

8 3,97 352,15

1/161,5

9 4,76 233,30

1/320,7

9 5,56 115,92


ia P

Temp. -20

o

F 800

o

F pulg mm mm

Lb/Pul

g2Ef. Tubo SinCost. Et 0,72 1/4

6,35 0,00 674,41


24/31


6 0,79 586,30


6 1,59 499,32

6,625 0,28 6,065 5/323,9

7 2,38 413,44

1/83,1

8 3,18 328,66

3/322,3

8 3,97 244,94

1/161,5

9 4,76 162,27

1/320,7

9 5,56 80,63

ces Services

Plugging

(On Land, Offshore)
http://www.conmatindia.com/product-details.aspx?pg=bv&cid=3&sid=6&iid=17http://www.conmatindia.com/product-details.aspx?pg=bv&cid=3&sid=6&iid=17http://www.conmatindia.com/product-details.aspx?pg=bv&cid=3&sid=6&iid=17http://www.conmatindia.com/product-details.aspx?pg=bv&cid=3&sid=6&iid=17http://www.conmatindia.com/product-details.aspx?pg=bv&cid=3&sid=6&iid=17


25/31

ess Flows

By-pass Systems

uum Gauge installation

onstruction

tallations

sample points

ons

oupling installation

r flow meters

nderwater service

n

ndicators

t Stop Services

n requires

itting is

pipe

pressure

stalled

A hot tap is made on

thepipe through the valveThe coupon is retained

byU-wires on the pilot drill

The hot tap machine

andcoupon are removed

The valve is closed

A sealing element is

selected for compatibility basedon the process, pressure and

temperature

The line stop machine is

attached to the valve

The line stop head seals

and isolates the section of pipe
http://www.conmatindia.com/Editor/images/users_images/line-stop-3-z.jpghttp://www.conmatindia.com/Editor/images/users_images/line-stop-2-z.jpghttp://www.conmatindia.com/Editor/images/users_images/line-stop-1-z.jpghttp://www.conmatindia.com/Editor/images/users_images/typical-hot-tap-z.jpg


26/31

sure is

stop head

SealTite

and locked

s

removed

uture date

nstalled

ops

e-Stop

functioning

ssels

chine is

valve

valve is

ew valve

machine is

Elbow Stop

A special SealTite fitting

is installed to the elbow

An angle tap is

performed on the elbow through a

temporary valve

The line stop is set and

the defective valve replaced

SealTite completion plug

is set and the temporary valve

removed

Across-The-Header-Stop

Applicable when

clearance limitation does not

permit normal line stopping

methods

A SealTite fitting is

welded to the header and a valve

is installed

A hot tap is made and the

plug is set

When the repairs are

complete the SealTite completion
http://www.conmatindia.com/Editor/images/users_images/across-the-header-stop-z.jpghttp://www.conmatindia.com/Editor/images/users_images/elbow-stop-z.jpghttp://www.conmatindia.com/Editor/images/users_images/through-the-valve-stop-z.jpghttp://www.conmatindia.com/Editor/images/users_images/line-stop-4-z.jpg


27/31

plug is set

lTite

fittingside of the

valve is

performed

lug passes

is set into

completion

temporary

ngs are welded to the line

ttings are welded to the line

ves are installed and two line stop taps completed

ops are set and the pressure is vented

een the two line stops is completed

are equalized and removed

etion plugs are set and the temporary valves removed
http://www.conmatindia.com/Editor/images/users_images/double-line-stop-z.jpghttp://www.conmatindia.com/Editor/images/users_images/tee-stop-z.jpg


28/31

d Bleed

fittings are welded to the line

ves are installed and two line stop taps completed

ops are set and the pressure is vented downstream of both line stopse stop holds the pressure while the secondary line stop ensures a 100% safe seal

nstream is completed

are equalized and removed

petion plugs are set and the temporary valves removed

estop

lass 150#, 66, 72, 78

tion Flange

etal Plug Seal Offers Greater Online Safety

g offers greater sealing strength with its metal-tometal seal

vides an additional safety for the completion plug

s are located on the SealTite Flanges recessed jack bolts
http://www.conmatindia.com/Editor/images/users_images/folding-head-linestop-3-z.jpghttp://www.conmatindia.com/Editor/images/users_images/folding-head-linestop-2-z.jpghttp://www.conmatindia.com/Editor/images/users_images/folding-head-linestop-1-z.jpghttp://www.conmatindia.com/Editor/images/users_images/double-block-and-bleed-2-z.jpghttp://www.conmatindia.com/Editor/images/users_images/double-block-and-bleed-1-z.jpg


29/31

Tite completion plug eliminates potential check valve leaks

ges can be safely utilized to re-enter the line at high temperatures and pressures

ges can be rebuilt online

pletion Flanges are available in stock for 150#, 300#, 600# and 900# flange ratings. 1500# and 2500#

able on request

fitting with

plug

SealTite Completion Plug

SealTite Flange Completion Plug

(Note recessed jack screws)

150# and

rature/high

Completion

ble upon

Line Plugging / Line StopLine plugging / Line stop is a method of temporarily isolating and bleeding down part of a

pressurized system, for purposes of alteration or maintenance within the isolated section. This is

done without shut down of the entire system and without loss of product. If flow must be

maintained, a temporary or permanent bypass can be installed around the isolated work

section.

Topaz is currently equipped for the following:

Low pressure Line plugging / Line stop: 1" through 48".

60 PSIG Maximum pressure @ 100F.

250F. Maximum temperature @ lower pressures High pressure Line plugging / Line stop: 2" through 16".

900 PSIG Maximum pressure @ 100F.

350F. Maximum temperature @ reduced pressures.

In addition to extreme pressure and temperature conditions, Topaz is experienced with

applications involving particularly volatile, corrosive, and toxic products.
http://www.conmatindia.com/Editor/images/users_images/sea-ltite-4-z.jpghttp://www.conmatindia.com/Editor/images/users_images/sea-ltite-3-z.jpghttp://www.conmatindia.com/Editor/images/users_images/sea-ltite-2-z.jpghttp://www.conmatindia.com/Editor/images/users_images/sea-ltite-1-z.jpg


30/31

Fittings and valves:

Topaz maintains a large inventory of completion style fittings in common sizes and flange

ratings for use in low and high-pressure line plugging services / line stop applications. These

specialty fittings allow us to work through temporary valves, which Topaz provides, during the

plugging operation. Once the repair or modification within the isolated work section is finished,

we secure an o-ring sealed metal plug in the fitting below the temporary valve. Pressure is thenbled off above the plug, the valve is removed, and a blind flange is installed on the fitting to

complete the job. If necessary, line plugging / line stopping work can also be performed through

permanent valves and standard hot tap fittings. When plugging through permanent valves,

contact Topaz for required bore diameters and overall fitting and valve dimensions prior to

welding.

Information we require for line plugging services / line stopping services:

Nominal size of the line. Will line be plugged on one end or both ends of isolated section?

Material and wall thickness (schedule) of the line.

Product in the line.

Operating pressure and temperature.

Maximum possible pressure and temperature while line is plugged.

Blowdown and equalization provisions for depressuring and repressuring of work

section.

Size of bypass, if required.

Scope of alteration or maintenance while line is plugged.

Orientation of the line and required fitting orientation.


31/31

pop Hot tap REV 00

Documents

Transcript of pop Hot tap REV 00