Technical Document

http://www.natoll.Gom NATIONAL OILWELL VARCO

TABLE OF CONTENTS

1.0. SCOPE ......................................................................... 2

2.0. REFERENCE ..................................................................... 3

3.0. National Aerospace Standard, Fluid cleanliness1CLEANLINESS ..................... 4 3.1. Cleaning of tubes during and after pre-fabrication - General guide: .... 4 3.1.1. Mechanical cleaning of tubes ........................................... 4 3.1.2. Chemical cleaning of tubes ............................................. 4 3.1.3. Alkaline degreasing .................................................... 4 3.1.4. Water rinsing .......................................................... 4 3.1.5. Pickling (only Carbon pipes and not to seamless cold drawn SS pipes) ... 4 3.1.6. Alternative pickling (supplier’s request) .............................. 4 3.1.7. Phosphoric acid pickling ............................................... 4 3.1.8. Water rinsing .......................................................... 4 3.1.9. Neutralisation ......................................................... 5 3.1.10. Water rinsing .......................................................... 5 3.1.11. Drying ................................................................. 5 3.1.12. Surface treatment ...................................................... 5 3.1.13. Passivation of Stainless Steel Pipes ................................... 5 3.1.14. Storage of tubes and tube parts ........................................ 6

4.0. FLUSHING ...................................................................... 7 4.1. Preparation of a Flushing Plan ......................................... 7 4.2. Hydraulic Pipe Flushing ................................................ 7 4.2.1. Specification of Flushing Flow ......................................... 7 4.2.2. Equipment needed during flushing ....................................... 8 4.2.3. Eventual 250-ml sample bottle, which is cleaned and sealed of a

certified supplier.Check List to be made up before flushing ............ 8 4.3. Water Pipe Flushing (Hydro flushing) ................................... 9 4.4. Air Pipe Flushing - Pressurised air shock blowing (PAS) ............... 10 4.5. Mud, Cement and Vent Pipe Flushing See NORSOK L-CR-004 ................ 10 4.6. Pneumatic flushing .................................................... 10

5.0. INSPECTION OF CLEANLINESS LEVEL .............................................. 11 5.1. OFF line automatic particle counter ................................... 11 5.2. Fluid sampling ........................................................ 11 5.3. ON line automatic particle counter .................................... 11

6.0. PRESERVATION ................................................................. 12

7.0. DOCUMENTATION ................................................................ 12 7.1. General ............................................................... 12 7.2. Completion Records .................................................... 12 7.3. Completion Record Sheet example ....................................... 12

8.0. QA & SAFETY .................................................................. 13 8.1. Quality Assurance ..................................................... 13 8.2. ISO 4406 SCALE NUMBERS - Basis of code ................................ 13

9.0. COMPLETION RECORD SHEET EXAMPLE .............................................. 14

2


1.0. SCOPE

This Procedure regards the Flushing of:

Hydraulic Piping Ring Line System and the corresponding

Equipment

Water Pipes for cooling of HPU, HP-washing and Utility Water

Air Pipes for Utility an Instrument Air

Mud - Cement - Vent Pipes

In accordance with the Block Diagram V1000-D1006-H0001, 2 and 3 and the

specifications referred to. This Specification, applies to the three categories:

Equipment Packages, Cranes and Ring Line Systems

Reynolds factor requirement under 5.2.1 below, applies to Equipment and Cranes

as well as the Ring Line System,

Equipment

Packages

Flushed with

separate HPU

This

Procedure

Reynolds

No. 4000 Delivered Sealed Clean

Ring Line

System

Flushed with

separate Test HPU

This

Procedure

Reynolds

No. 4000

Commissioned according to

this Procedure

Flushing of systems is based on a controlled start-up where the cleanliness

level is achieved through continuously filtration and monitoring with a particle

counter.

This Flushing Procedure in the order of schedules:

1. Cleaning of Tubes and Pipes prior to assembly.

2. Assembling of fixed Ring Line pipe works.

3. Cleaning

4. Pressure Testing (SS Systems prior to Flushing - CS Systems after

Flushing)

5. Flushing (This Procedure)

6. Preservation of fixed Ring Line pipe works.

7. Clean assembling of Equipment to the fixed Ring Line pipe works.

8. Ring Line Leak Testing at Working Pressure, of the complete system

assembly

9. Leak Testing Repeat after Equipment Test & Trial.

10. Any unsuccessful part of the process requires repetition before

proceeding.

3


2.0. REFERENCE

The P.O specification and this Specification of the corresponding internal

National Oilwell Varco practise are ruling to all Suppliers and Sub-Suppliers

through all stages in the development of the System. Consequently any other

Reference should be waived by the Client in due time.

References for National Oilwell Varco guidance are:

National Oilwell Hydraulic Hand Book Rev.2 10.08.99

National Oilwell HL/T-16 PreservationNORSOK L-002

National Oilwell ISO 4021

NORSOK L-CR-004 and ANNEX B:

NORSOK Z-006 V1000-D1011-H0001, 2 & 3 NAS 1638

Piping Design, Layout and Stress Analysis Clean Mounting

(Report Format)

Oil Sampling

Piping Fabrication, Installation, Flushing and Testing,

Requirements for internal treatment of piping after prefab and

installation before commissioning.

Preservation of equipment and systems

Hydraulic Block Diagrams

4


3.0. National Aerospace Standard, Fluid cleanliness1CLEANLINESS

3.1. Cleaning of tubes during and after pre-fabrication - General guide:

3.1.1. Mechanical cleaning of tubes

After mechanical cleaning, tubes and tube flanges shall be smooth

and free from slag, welding beads, baking, pores and foreign

particles. Sandblasting shall not take place.

3.1.2. Chemical cleaning of tubes

Tubes with scale and/or corrosion shall be treated according to the

following procedure: Alkaline degreasing - Water rinsing - Pickling

- Water rinsing - Neutralising - Water rinsing - Drying.

3.1.3. Alkaline degreasing

The tubes are to be cleaned with an approved degreasing agent oil

and grease reduce the effect of the pickling process. An alkaline

bath which removes most of the organic dirt (lacquer, oil, fat) may

consist of 10% NaOH (caustic soda) and 90% water. Treatment time is

approximately one hour at 90 degr.°C. Certain types of fat are not

removed by this procedure.

3.1.4. Water rinsing

The tubes are to be thoroughly washed with fresh water.

3.1.5. Pickling (only Carbon pipes and not to seamless cold drawn SS pipes)

The tubes are preferably pickled in a sulphuric acid bath consisting

of: 10% ÷ 20% H2SO4 (sulphuric acid in water, 1 ÷ 2 m/l Inhibitor

(Hexamine). Maximum bath temperature, 80°C. Alternatively the tubes

are filled completely with pickling fluid. Always pour acid

concentration into water, not vice versa. The acids must be treated

carefully as they are highly corrosive. Protect skin and eyes and

follow the recommendations of the acid supplier.

3.1.6. Alternative pickling (supplier’s request)

Pickling in hydrochloric acid 50 % HCI (Hydrochloric acid in 35%

concentration, non-arsenic) in water, 1 -2 ml/l Inhibitor

(Hexamine). Maximum bath temperature: 35°C, Pickling time: 10-60

min. Hydrochloric acid is very active and leads to immediate

corrosion if neutralisation measures are not taken immediately after

the pickling. However, pickling in hydrochloric acid may lead to

hydrogen embrittlement in the steel if the inhibitor is not

efficient enough.

3.1.7. Phosphoric acid pickling

Phosphoric acid pickling gives a small amount of corrosion and

normally requires no neutralisation.


The tubes are to be washed thoroughly with fresh water immediately

after the acid pickling.

5


3.1.9. Neutralisation

The tubes are to be washed with an adequate neutralising liquid. An

adequate neutralising liquid may consist of 2 % NasP04 (trinatrium

phosphate) in water. Bath temperature’s from 80 ÷ 90°C. Treatment

time’s from 1 ÷ 2 minutes.


The tubes shall be washed thoroughly with fresh water to remove the

neutralising liquid.

3.1.11. Drying

The tubes shall be dried with warm, dry air within 30 minutes after

the water rinsing.

3.1.12. Surface treatment

To maintain the obtained until installation, the tubes shall be

treated with a suitable protection liquid. The liquid used should

give protection against corrosion at least for five months after the

properties of the flushing fluid or system oil.

3.1.13. Passivation of Stainless Steel Pipes

Bare stainless steel will rust and corrode in the presence of iron

particles or filings until a chromic oxide film develops on the

surface when exposed to oxygen in the air The passivating process is

used to hasten and enhance the creation of this oxide as well as to

develop a thicker and tougher film. The surface should be cleaned

first before passivating. Swabbing with the passivating solution

will remove most loose solids. In extreme cases a preliminary acid

wash may be used for cleaning if it is neutralised and rinsed away

prior to passivation

The following solutions are used passivating stainless steel

(for 316L tube/pipe):

Solution A:

For series 200 and 300, and chromium grades

containing 17% Cr. or more.

70% nitric acid (HN03) 6-15% (Vol.)

Water, clean and fresh Remainder

Operating temperature Room

Contact time 10-30 minutes

Solution B:

For free-machining grades, polished surf,

and series 400 with less than 17% Cr.

70% nitric acid (HNO3) 18-25% (Vol.)

Sodium dichromate (Naz, Cr2Oi, ZH20) 2% (Wt.)

Water, clean and fresh Remainder

Operating temperature Room or 120°F

Contact time 10-30 minutes

Passivating is accomplished as follows:

6


Immerse, flush or swab with passivation solution.

Flush the surface with clean fresh water (not sea water) to

remove all traces of acid. Subsequent ’’rust proofing” by

coating with oil or hydraulic fluid is unnecessary and

undesirable since this film serves only to hold dust and dirt.

It is important to close all pipe openings to carefully guard

against the entry of dirt until final installation is

complete.

Do not clean Stainless Steel Pipes with a wire brush as traces of

iron because it’s may be left on the surface.

3.1.14. Storage of tubes and tube parts

Cleaned and surface treated tubes and fittings have to be capped

immediately and should be stored in a dry place.

7


4.0. FLUSHING

4.1. Preparation of a Flushing Plan

A Flushing Plan including Block Diagram for the specific system shall be

prepared. Special equipment for the Flushing, like supporting equipment,

loops, couplings, connectors etc. shall be listed and sketched at the

diagrams.

Cleaning shall be carried out prior to pressure testing and the Flushing

thereafter. General requirements for Flushing for specific systems are

listed in NORSOK L-CR-004 - table 1 in Annex B National Oilwell Varco

shall approve the Flushing Plan.

4.2. Hydraulic Pipe Flushing

Flushing of the Ring Line Piping System shall be performed in accordance

with the References noted and as a minimum satisfy:

NAS 1638 class 8 ♦ ISO 4406 17/14.

4.2.1. Specification of Flushing Flow

During the flushing of the pipes, it is necessary to reach turbulent

conditions in order to ensure efficient removal of and transport of

particles with the flow. The Reynolds number defines turbulent

conditions and is given by the equation 1:

Q is the flow in the pipeline given in litre/minute D is the inner

diameter given in millimetres vis cinematic viscosity given in

centistokes

The numerical value of Reynolds number defines all the different

flow regimes:

Laminar Flow Re < 2300

Transition between turbulent and laminar flow 2300 < Re < 4000

Fully turbulent flow Re > 4000

Re>3000 is defined as turbulent conditions during flushing. For long

pipelines and especially pipes with diameter less than 15 mm, the

pressure drop must be controlled according to the required flow with

equation 2. Viscosity is the only parameter that both increases the

flow and decreases the pressure drop. The flushing fluid should be

compatible with the operating fluid, re. Equation 2:

In the Alignment Chart below, practical combinations of flow, pipe

diameters and viscosity at Reynolds number 3000 are given. If

required to flush at higher Reynolds number, the equations referred

to should calculate the flow.

8


4.1 - Alignment Chart to find the required flow

to achieve turbulent conditions.

4.2.2. Equipment needed during flushing

Flushing-unit, use another HPU with sufficient capacity

(Yard).

Thermometer

Particle counter

As per oil heater required, various hoses with couplings, caps

and tools.

4.2.3. Eventual 250-ml sample bottle, which is cleaned and sealed of a

certified supplier.Check List to be made up before flushing

Check that the system is assembled with reference to the hydraulic

design requirements and the Flushing Plan approved by National

Oilwell Varco, including National Oilwell Varco approved report

regarding CLEAN MOUNTING.

1. Check that all leaks are sealed/tightened as required.

2. Inspect the oil level in the Reservoir. The Reservoir shall be

filled through filters of specified sizes up to normal level

of the Reservoir.

3. Check that all manually operated (normally open) test valves

are fully open (e.g. globe and gate valve).

4. Loop together all supply ports (pump and tank ports) In the

Ring Line Main with hoses and valves in accordance with the

Sketch below (Port Loop).

5. The ends of the Ring Main also looped together (End Loop).

6. Ensure that the system designer's Flushing Assembly

Instructions are met and check out the Plan with a Yellow

Marker and sign.

9


1. Start the pumps and filtrate the oil internally in the HPU

until NAS 1638 class 8 (ISO 4406 code 17/14) is achieved.

2. Circulate the oil and bleed air until the system is filled

with oil.

3. Heat the oil during running to 55÷60°C for VG 32 oil (60÷65°C

for VG 46 oil)1. The temperature shall be measured in the

reservoir. If this temperature is not possible to achieve

during normal running, a heater should be mounted and used.

4. Run flow through the port loops one loop at a time. Open the

valve with full effort for 3 minutes. Run through the rest of

the port loops in the same way.

5. Run the moving elements (actuator, hydraulic motor, etc.) one

by one.

6. Actuators are to be run with full effort at least 10 times in

each direction. Hydraulic motors are to be run with full

effort for 3 min. in each direction.

7. Monitor the cleanliness level with a particle counter. Sample

from the return line close to the return filter. Let at least

5 litres of oil circulate through the counter before sampling.

If the sample has NAS class 8 (ISO 17/14) or better, two new

samples shall be taken at once. If the target cleanliness

level is not achieved and it is over NAS class 11 stop the

pumps2. If the NAS class is between 8 and 11 repeat the

procedure with running of the moving elements until target

cleanliness level NAS class 8 is achieved.

8. The responsible person shall sign the specific equipments test

printouts from the particle counter which shall be attached to

the complete report.

4.3. Water Pipe Flushing (Hydro flushing)

See NORSOK L-CR-004 chapter 8, item 8.2; quote: “Chapter 8, item 8.2,

Hydro flushing: Items of equipment which would be sensitive to damage

during hydro flushing shall be removed, blocked or isolated. A list shall

be prepared and be part of the flush & test procedure.

Ball valves shall be flushed in fully open position.

All piping systems shall be flushed using high pressure jet flushing

equipment, such as rotating hose or rotating nozzle. Minimum pressure

shall be 600 Bar.

Below 4”, High Velocity Water Flushing (HVWF) may be used. Water velocity

shall be a minimum of 10m/s. On systems where high pressure jet flushing

cannot be used due to complicated shapes and/or long runs HVWF may be

used.

The flushing medium shall in general be fresh water. When flushing

stainless steel lines, the chloride ion content shall be less than 200ppm.

After flushing, the piping systems shall be completely drained and

protected against corrosion.

Ball valves shall be flushed fully open.”

1 Because of pump breakdown, the viscosity never should be lower then 16 cSt. The

viscosity is 16 cSt at 62°C for VG 32 oil and at 72°C for VG46 oil. These

temperatures must never be exceeded. 2 The superior that is responsible for the flushing is to be contacted for

consultation. Proportional valves are to be removed from the system and bypasses

put on the valve block.

10


4.4. Air Pipe Flushing - Pressurised air shock blowing (PAS)

See NORSOK L-CR-004 chapter 8, item 8.3. We quote: “Chapter 8, item 8.3,

pressurised air shock blowing:

This meted may be used as an initial cleaning method for instrument air,

plant air and as an alternative method for initial cleaning of small bore

pipe (less than 2”). This method may also be used when there are problems

removing trapped liquid in the circuit, or to verify cleanliness of small

bore pipe where video inspection is impossible or inadequate due to pipe

dimension or configuration.

When using PAS method for cleaning or verification the procedure shall be

repeated until cleanliness is acceptable.

The air shocking pressure shall never exceed the working pressure of the

system and shall never be more than 8 Bar. Safety precaution shall be

taken when this method is used.

4.5. Mud, Cement and Vent Pipe Flushing See NORSOK L-CR-004

See section 4.3. Water Pipe flushing

4.6. Pneumatic flushing

See NORSOK L-CR-004 chapter 8, item 8.4. We quote:

“Chapter 8, item 8.4, Pneumatic flushing:

In cases where water is not desirable in the piping system (e.q.

instrument / utility air), flushing by pressurised air or PAS shall be

carried out. When pressurised air is used, the minimum velocity shall be

35 m/s. Procedure covering all safety aspects shall be established.”

11


5.0. INSPECTION OF CLEANLINESS LEVEL

The obtained cleanliness level shall be documented before a flushing operation

may be considered as final. Use particle counter to control the solid particle

level and a titration instrument to control the water content.

5.1. OFF line automatic particle counter

This is the most common method. It is possible to use an external

laboratory with a up to date instrument or to rent the equipment - with

trained personnel - to analyse on site. The results shall be documented in

a Cleanliness Print out Certificate and signed.

5.2. Fluid sampling

Fluid Sampling is often underestimated. The frequency and quality of the

sampling is vital for the monitoring of the process and the documentation.

The location of the sampling point is downstream (Return Line).

Oil samples only to be taken as dynamic sampling

There are several designs of samplings points, but very few to give a

representative oil sample. One recommended system to follow is ISO 4021.

The sampling bottles shall be special cleaned and prepared bottle of at

least 100 ml, 250 ml is preferred.

The supplier of the prepared bottles shall be able to document the

cleanliness level of the prepared bottles.

5.3. ON line automatic particle counter

This is a very sensitive method that has to be handled with care. Only

specially trained personnel are qualified to install and operate such

equipment.

The major advantage of this method is a full control with the cleanliness

level at all times during the process. Equipment that can shut down the

flushing station after having reached the recommended cleanness level and

made print outs automatically, is available.

Another advantage is the elimination of uncertainty caused by sample

bottles and external handling of the samples.

It is recommended, however, to always send one sample of each flushing

operation to an external laboratory as a final documentation.

12


6.0. PRESERVATION

Ring line system in derrick to be sealed off with blind flanges and solid

caps/plugs after flushing.

7.0. DOCUMENTATION

7.1. General

Documentation requirements are generally in accordance with: Technical

Specification of Piping Installation.

Pressure Testing for National Oilwell Varco Equipment.

7.2. Completion Records

Completion Record Sheets shall be developed by the Supplier in order to

fulfil the requirements of the Client and National Oilwell Varco. National

Oilwell Varco shall approve the lay-out of the Completion Records as a

part of the Flushing Plan (see 5.1).

7.3. Completion Record Sheet example

Attached to this Specification is an example of Completion Record Sheet,

suitable for Hydraulic Piping Service tests. Adequate Sheets shall be

developed for other Service Codes.

13


8.0. QA & SAFETY

8.1. Quality Assurance

Quality Assurance requirements are generally in accordance with the

Quality Plan. Safety requirements - see Pressure Testing

Procedure.CONTAMINATION CODES

Comparison of Contamination Codes against other commonly used cleanliness

classes are given in the following table:

Table 8.1 - APPROXIMATE EQUIVALENTS OF CONTAMINATION CLASSES

BS 5540/4

ISO/DIS 4406 CODE NAS 1638 CLASS SAE 749 CLASS

11/8 2 -

12/9 3 0

13/10 4 1

14/9 - -

14/11 5 2

15/9 - -

15/10 - -

15/12 6 3

16/10 - -

16/11 - -

16/13 7 -

17/11 - -

17/14 8 -

18/12 - -

18/13 - -

18/15 9 6

19/13 - -

19/16 10 -

20/13 - -

20/17 11 -

21/14 - -

21/18 12 -

22/15 - -

23/17 - -

NOTE: The above comparisons relate to particle count data only. To

conform to any particular standard, reference should be made to the

recommended experimental procedure.

8.2. ISO 4406 SCALE NUMBERS - Basis of code

The code number corresponding to a pollution level comprises two scale

numbers, which permits the differentiation of the dimension and the

distribution of the particles as follows:

The first scale number is the number of particles > 5 um per

milliliter of fluid.

The second scale number is the number of particles > 15 um per

milliliter of fluid.

14


Allocation of scale numbers:

The scale numbers are attributed according to the number of particles

counted large than um and 15 um respectively, yielded in 1 ml. of fluid

(see the table).

Number of particles per milliliter Scale

number More than Up to and including

80 000 160 000 24

40 000 80 000 23

20 000 40 000 22

10 000 20 000 21

5 000 10 000 20

2 500 5 000 19

1 300 2 500 18

640 1 300 17

320 640 16

160 320 15

80 160 14

40 80 13

20 40 12

10 20 11

5 10 10

2,5 5 9

1,3 2,5 8

9.0. COMPLETION RECORD SHEET EXAMPLE

Note: This completion record sheet and Hydraulic Block Diagram with the flushing

loop marked and the result of the oil sample must be stored in a flushing record

book as a final documentation of the flushing.

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