Necessary testing during installation of HDPE Pipe Force Main? 4

[kfeng]

I'm preparing Specs for a HDPE pipe force main. Does anyone know where I can find related information? I specified that Approved Products are Plexco HDPE pipe and approved equal.
But wasn't able to find information regarding testing in their website.

Thank you very much for any suggestion. Have a good weekend!

 

[anfeng]

from the Driscopipe web site,


PRESSURE TESTING DRISCOPIPE SYSTEMS
Driscopipe piping systems should be pressure tested before being put into service. Water is the
preferred test medium. After all free air is removed from the test section, raise the pressure at a
steady rate to the required pressure. The pressure in the section shall be measured as close as
possible to the lowest point of the test section.
The pressure test can be conducted before or after the line is backfilled. The pipe should be covered
at intervals, particularly at curves to hold it in place during pressure tests. Flanged connections may
be left exposed for visual leak inspection.
Test pressure should not exceed 1.5 times the rated operating pressure of the pipe or the lowest rated
component in the system. Initially, the pipe should be raised to test pressure and allowed to stand
without makeup pressure for a sufficient time to allow for expansion of the pipe. This usually occurs
within 2-3 hours. After equilibrium is established, the test section is pressurized to 1.5 times
operating pressure, the pump is turned off, and the final test pressure is held for 1, 2, or 3 hours.
Polyethylene pipe holds pressure by developing stress in its walls. This process continues throughout
the test period and the pipe increases slightly in diameter. Pressure drop will occur due to continued
expansion of the pipe during the second phase of the test. A drop in pressure during the test phase is
common and does not prove with absolute certainty that a leak or failure is present in the system.
Polyethylene pipe is tested by measuring the “make up” water required to return the section to test
pressure. Allowable amounts of makeup water for expansion during the pressure test are shown in
Table 16 from PPI Technical Report TR 31. If the test pressure is not returned within the allowable
volume of water, the test fails. If there are no visual leaks or significant pressure drops during the final
test period, the pipeline passes the test.

 

[kcalderwood]

Keep in mind that as your HDPE pipe expands slightly in diameter during testing, it will also contract (or try to contract) in length. You need to be sure to properly anchor the pipe ends, or allow for this contraction. Since your test pressure us usually larger than operating pressure, this will be the limiting case...if you account for the contraction during testing, you should be OK in service.

 

[CarlB]

I'll prefrace this with saying I've never been involved in a pressure test of an HDPE piping system, but if what kcalderwood says is true I'd be intersested in what causes this unusual phenomenum. Everything I've learned in properties of materials tells me the pipe under internal pressure will want to expand radially and longitudinally, not contract in length. The presuure acts outwards everywhere, the pipe will want to lengthen. But there's no need to anchor a buried HDPE pipe in most cases, the soil friction along the pipe should normally resist expansion or thrust forces. May be exceptions, such as bend near an end, but there's no concern with joint separation.

Let me know if I'm "all wet" on this one.

Regards,
Carl

 

[stanier]

The test methods developed in Europe and adopted in Australia are more sophisticated than as described for the Driscopipe.

A book by Borealis authored by Prof. Lars-Eric Janson is considered the authoritarian text on this subject.. Suggest you look on the

http://www.auspoly.asn.au/Docs/TP005.html

website for notes on the rebound test method.

 

In response to carlb's question about a pipe under internal pressure wanting to shrink longitudinally, the "phenomenum" is caused by what is known as the Poisson's effect. By definition, a material's poisson's number is the negative ratio of the strain in the y direction to the strain in the x direction. Therefore, if a material is lengthened in one direction it will shorten in the transverse direction. This is why a pipe under internal pressure will try to contract along its length. Since stress is proportional to the strain by the modulus of elasticity (Hooke's law) this strain can be "converted" to a force by multiplying by the modulus and the cross sectional area. This force can be quite significant under large pressures, enough to pull the PE out of unrestrained couplings. There are some end forces on a pressurized pipe with a capped end that are trying to push outward but on a long pipeline, these are very localized and rather insignificant in relation to the amount force trying to contract the pipeline.

I hope this helps.

 

[stanier]

Does this extract help?

FIELD TESTING

6.1 PURPOSE
The purpose of field testing is to:
(a) reveal the occurrence of faults in the laying procedure, e.g. joints incorrectly installed or pipes damaged;
(b) reveal the occurrence of faults in the assembly procedure of pipeline components, e.g. tapping bands, maintenance structures, frames and covers;
(c) in the case of pressure pipelines, determine that the pipeline will sustain a pressure greater than its design pressure without leakage;
(d) in the case of non-pressure pipelines, determine that the pipeline satisfies the requirements for infiltration and exfiltration; and
(e) test the installed structural integrity of the pipeline;
Field testing is not intended to supplement or replace the test requirements of product Standards.
6.2 PRESSURE PIPELINES - HYDROSTATIC PRESSURE TESTING
6.2.1 General
The hydrostatic pressure test method shall be as specified.
Hydrostatic pressure testing requires selecting an appropriate configuration of method, pressure and length of test section.
Test parameters and details shall be determined with due consideration to the following:
(a) pipe material;
(b) pipe diameter
(c) length of test section;
(d) magnitude of test pressure, rate of pressurisation and duration of the test;
(e) presence of air in the pipeline;
(f) time required for saturation of porous liners;
(g) potential movement of pipeline thrust restraints;
(h) design pressure for thrust and anchor supports;
(i) accuracy of test equipment;
(j) ambient temperature changes during testing;
(k) presence of leaks in equipment used for testing or equipment attachment points (e.g. sealing plugs); and
(l) potential for leaks in the pipeline.
NOTE: It is advisable to begin testing early in the pipeline installation to confirm adequacy of laying procedures, and where appropriate, to increase the length tested progressively as experience is gained.
6.2.2 Selection of test pressure
The hydrostatic test pressure at any point in the pipeline shall be:
(a) Not less than the design pressure;
(b) Not more than 25% above the rated pressure of any pipeline component.
NOTE: The design pressure includes the short term surge pressure (water hammer) as determined by analysis (see Clause 1.4.8).
Compressed air testing shall be carried out in accordance with Clause 6.4.2.
NOTE: Air test pressures in excess of 50 kPa should not be applied due to safety considerations.
6.2.3 Selecting test lengths
The pipeline length tested shall be either the whole, or a section (capable of being isolated), of the pipeline depending on the length and diameter, the availability of water and the spacing between sectioning valves or blank ends.
The pipeline shall be divided into test sections such that:
(a) The hydrostatic test pressure at any point in the pipeline is —
(i) Not less than the design pressure;
(ii) Not more than 25% above the rated pressure of any pipeline component.
(b) Water is available for the test together with facilities for its disposal, in accordance with regulatory requirements, after the test.
NOTES:
1 Pipelines longer than 1000 m may need to be tested in several sections. Where long lengths are to be tested, radio or other electronic means of communication between test operatives, to coordinate test procedures and thus minimise the test duration, is desirable.
2 Long test sections may incorporate a large number of mechanical (i.e. flanged) joints, which should be checked for leakage. The longer the test section the harder it is to locate a leak, or discriminate between a leak and the other effects, such as the absorption of air into solution under pressure.
6.2.4 Pressure test methods
6.2.4.1 Constant pressure (water loss) method
The test length shall be hydrostatically pressure tested in accordance with Appendix M, Paragraph M4.
NOTE: This method is suitable to DI, GRP, PVC, and steel pipelines.
The test length shall be acceptable where:
(a) there is no failure of any thrust block, pipe, fitting, joint or any other pipeline component;
(b) there is no visible leakage; and
(c) The quantity of make-up water necessary to maintain the test pressure shall comply with the following Equation:
. . . 6(1)
where,
Q = allowable make-up water, in litres per hour
D = nominal diameter of the test length, in metres
L = length of the test length, in kilometres
H = average test head over length of pipeline under test, in metres
NOTE: The make-up water is not a leakage allowance, but is an allowance to cover the effects of the test head forcing small quantities of entrapped air into solution. Normally the test should last for a minimum of 2 h and be concluded within 5 h to 8 h. The make up water requirement should reduce with time as air goes into solution. Where, after 12 h the make up water still exceeds the allowable limit, testing should cease and the cause of loss investigated.
6.2.4.2 Constant pressure (water loss) method for visco-elastic pressure pipelines
The test length shall be hydrostatically pressure tested in accordance with Appendix M, Paragraph M5.
NOTES:
1 This method is suitable for PE, PP and ABS pipelines.
2 Visco-elastic materials exhibit significant creep and hence the method given in Clause 6.3.4.1 is not appropriate.
3 This method is based on VAV P78.
The test length shall be acceptable where—
(a) there is no failure of any thrust block, pipe, fitting, joint or any other pipeline component;
(b) there is no visible leakage;
(c) the allowable make-up water, used to maintain the test pressure, shall be less than the quantity calculated from Equation 6(1).
6.2.4.3 Pressure decay method for visco-elastic pipelines
The test length shall be hydrostatically tested in accordance with Appendix M, Paragraph M6.
NOTES:
1 This method has been validated for PE pipelines, however, it may be used for other materials given appropriate test data.
2 Visco-elastic materials exhibit significant creep and hence the method given in Clause 6.3.4.1 is inappropriate.
3 This method is based on - Section 5 of 'A guide to testing of water supply pipelines and sewer rising mains', 1st Edition, June 1999, published by Water Research Committee (WRc Plc), UK.
The test length shall be acceptable where:
(a) there is no failure of any thrust block, pipe, fitting, joint or any other pipeline component;
(b) there is no visible leakage; and
(c) it passes the criteria of Appendix M, Paragraph M6.
NOTES:
1 When the test pressure is applied to a leak-free test section, there may be a reduction in pressure (pressure decay) in a non-linear manner, due to the creep response and stress relaxation of the material (see Figure 6.1(a)). Where the pressure decay is plotted against a logarithm of time, the result is expected to be a straight line (see Figure 6.1(b), line A-B). An increase in the slope of the line will indicate that there is leakage in the test section. A change to a steeper slope, as shown by line A-C, indicates the possibility of leakage.
2 Using the decay profile, the effect of leakage can be predicted by amending the calculation to take account of the drop in pressure due to the leak itself. The presence of any air trapped in the pipeline will also effect the shape of the line, since air is compressible and it will act to maintain the pressure over time. This will initially give a false reading. Line A-D, with an initial flatter slope, indicates air was present at the start of the test. The pressure loss method of Appendix M, Paragraph M5 gives guidance on the interpretation of different values for the slope of the line.

FIGURE 6.1 TYPICAL PRESSURE DECAY GRAPHS FOR PE PIPELINES
6.2.4.4 Pressure rebound method for visco-elastic pressure pipelines
The test length shall be hydrostatically tested in accordance with Appendix M, Paragraph M7.
NOTES:
1 This method is suitable for ABS, PE and PP pipelines, where a short test time is required.
2 Visco-elastic materials exhibit significant creep and hence the method given in Clause 6.3.4.1 is not appropriate.
Test pressures shall not exceed the operating pressure times any design or service factor for the material. Compressed air testing shall not be permitted for pressure pipe.
The test length shall be acceptable if—
(a) there is no failure of any thrust block, pipe, fitting, joint or any other pipeline component;
(b) there is no visible leakage;
(c) it complies with the criteria of Appendix M, Paragraph M7.
6.2.4.5 Visual test method for minor pipelines
The test length shall be hydrostatically pressure tested in accordance with Appendix M, Paragraph M8.
NOTE: This test may be appropriate for small installations of all materials, which are easily inspected visually for leaks.
The test length shall be acceptable where:
(a) there is no failure of any thrust block, pipe, fitting, joint or any other pipeline component;
(b) there is no visible leakage; and
(c) there is no pressure loss indicative of a leak.
6.2.4.6 Other test methods
NOTE: Testing may also be carried out in accordance with the material specific hydrostatic test methods of AS 2032, AS 2033 and AS 3690, for PVC, PE and ABS pressure pipelines, respectively.
6.3 NON-PRESSURE PIPELINES - LEAKAGE TESTING
6.3.1 General
Leakage testing is used to reveal locations of potential infiltration and exfiltration due to the inclusion of damaged pipes, seals or incorrectly made joints in the pipeline at the completion of installation.
Leakage testing for acceptance of non-pressure pipelines, shall be carried out by at least one of the following methods:
(a) low pressure air testing;
(b) vacuum testing;
(c) hydrostatic testing; and
(d) infiltration testing.
Leakage testing is not required for stormwater drains.
NOTE: Air and vacuum tests provide qualitative data only, as air pressure losses cannot be related directly to water leakage rates.
For pipeline test sections installed below the water table, and for submarine pipelines, the test pressure used for the hydrostatic test, and for the air test, shall be increased to maintain the required differential between internal and external pressure.
A pipeline failing to meet the requirements of the air or vacuum tests may be retested using the hydrostatic test method.
Failure is still probable.
6.3.2 Low pressure air test
The pipeline shall be tested in accordance with Appendix N, Paragraph N2.
The test length shall be acceptable where the gauged pressure exceeds 18 kPa (or 7 kPa less than at the pressure at the start of the test) for the time interval shown in Table 6.1 after the shut-off of the air supply.
This table is based on an air test pressure of 25 kPa (in excess of any external hydrostatic pressure due to groundwater) and, on this basis, air volume losses shall not exceed the greater of:
(a) a rate of 0.0009 m3/(minute ´ m2) of pipe wall area; and
(b) a rate of 0.056 m3/minute which is regarded as the lowest detectable individual air leak.
Column 2 and column 3 of Table 6.1 give the times and lengths up to which (b) prevails over (a).
NOTE: Air test pressures in excess of 50 kPa should not be applied due to safety considerations.
6.3.3 Vacuum Test
The pipeline shall be tested in accordance with Appendix N, Paragraph N3.
The test length shall be acceptable where the vacuum does not decrease in magnitude below (-)18 kPa (that is a maximum drop in vacuum of 7 kPa) over the time interval shown in Table 6.1.
6.3.4 Hydrostatic test
The pipeline shall be tested in accordance with Appendix N, Paragraph N4.
The test length shall be acceptable, where the specified allowable make up water is not exceeded. Where not specified, the allowable make up water shall be 0.5 litres per hour per metre length per metre diameter.
6.3.5 Infiltration Test
The pipeline shall be tested in accordance with Appendix N, Paragraph N5.
The test length shall be acceptable where there is no infiltration over a 24 hour period.
NOTE: Where a free-standing water table is present at a level of at least 1.5 m above the test section, and 150 mm above any sideline connections, the absence of infiltration can eliminate the need for any of the previous tests.
An allowance for infiltration may be acceptable subject to approval.
TABLE 6.1
LOW PRESSURE AIR AND VACUUM TESTS—MINIMUM TIME INTERVALS FOR 7 KPA PRESSURE CHANGE IN PIPELINE
DN Minimum time(minutes) Maximum length for minimum time to apply(metres) Test length (metres)
50 100 150 200 250
Minimum test duration (minutes)
80100150 1.523 231185123 1.523 1.523 1.523 1.525 1.636
225300375 467 826249 467 5914 81422 101829 132336
450525600 91011 413531 101418 212837 314255 415673 527092
675750900 131417 272521 232941 465783 7086124 93115165 116143207
100010501200 192023 1918.815 515673 102112147 153169220 204225294 255281367
1500 28 12 115 230 344 459 574
NOTES: 1 The time interval may be reduced for a proportionate reduction in the allowable pressure drop. Where there is no detectable change in pressure after 1 hour of testing, the section under test shall be deemed acceptable.2 This table is based on the following equation: where,T = time for a 7 kPa pressure drop (seconds);Di = pipeline internal diameter ( metres);q = allowable volume loss in cubic metre/minute/ square metre taken as 0.0009 m3/min.m2 in Table 5.2;k = 0.054DL but not less than 1; andL = length of test section (metres).3 Columns 2 and 3 have been calculated with k=1.0.4 The appropriate air or vacuum test/ pressure method for pipes larger than DN 750 should be established by reference to the specifier.
6.4 DEFLECTION TESTING
6.4.1 General
For non pressure pipelines, and where structural verification for pressure pipelines is required, deflection shall comply with the test criteria of Table 5.6.
The allowable short term deflections of Table 5.6 are based on 30 day time intervals after embedment (and fill) placement and compaction. Where measurements are made over an alternative time interval, the allowable deflections shall be determined by multiplying the values in Table 5.6 by the appropriate time factor given in Table 6.2.
NOTE: Deflection measurement is a valuable method of assessing the adequacy of embedment material placement and compaction. Testing may be carried out as soon as practicable after completion of placement and compaction of all fill material over the pipeline.
TABLE 6.2
TIME FACTORS FOR DEFLECTIONS
(to adjust allowable 30 day deflections given in Table 5.6)
Time interval Factor
24 hours3 days7 days 0.700.750.85
14 days30 days3 months 0.951.01.1
1 year2 years 1.21.3
NOTE: Factor values may be interpolated for intervening time periods between 24 hours and 2 years. E.g. for 10 days=0.85+((0.95-0.85)´3/7)=0.89
6.4.2 Pipelines - less than 750 mm diameter
The pipeline shall be tested in accordance with Appendix O, Paragraph O2.
The pipeline shall be acceptable where the prover passes through the test section showing that the actual short-term deflection is less than that specified in Table 5.6, amended according to Table 6.1, where appropriate.
6.4.3 Pipelines - greater than or equal to 750 mm diameter
The pipeline shall be tested in accordance with Appendix O, Paragraph O3.
The pipeline shall be acceptable where the actual short-term vertical pipe deflection, calculated from Equation O(1), is less than that specified in Table 5.6, amended according to Table 6.1, where appropriate.
SECTION 7 COMMISSIONING
7.1 GENERAL
Acceptance criteria shall be approved by the service owner.
No pipeline shall be placed in service before it has been cleaned of contaminants, before it has satisfied test requirements and, in the case of drinking water pipelines, before the quality of water supplied from the pipeline has met the asset owner’s standards.
Possible contaminants may include—
(a) materials that enter the pipes and fittings during storage and transport;
(b) materials introduced during construction;
(c) bacterial contaminants, which often colonize other contaminants;
(d) infiltration.
7.2 CLEANING WATER SUPPLY PIPELINES
New and repaired water supply pipelines shall be cleaned using the following procedure:
(a) Slowly fill the pipeline;
(b) Clean by;
(i) Swabbing, followed by flushing to completely turn-over the water contained in the pipeline;
(ii) Air scouring (i.e. where compressed air is injected into the water in the main to create unsteady flow conditions during the flushing process);
NOTE: Generally not as effective and usually more difficult than swabbing.
(iii) High velocity flushing (e.g. 2 m/s to 2.5 m/s for 15 minutes).
NOTE: Generally not practical or possible for water mains >DN 300.
7.3 DISINFECTION OF DRINKING WATER SUPPLY PIPELINES
7.3.1 Cleaning
Drinking water supply pipelines, shall be cleaned in accordance with Clause 7.2 and in accordance with any additional requirements of the asset owner.
7.3.2 Disinfection
Drinking water supply pipelines shall be disinfected using the following procedure:
(a) Fill and disinfect;
(b) Flush or neutralise or both;
(c) Refill the main;
(d) Sample for the presence of bacteria;
(e) Certify acceptance; and
(f) Introduce the main into service.

 

[ayoob]

Dear,
I'll be very grateful to you if you can guide me how to submit my question/problem? & get answered be the forum.

Thanx

My email:khattiayoob@yahoo.com

 

[knowitall]

1 month old and time to update your spec kfeng.
Plexco disappered in a merger with Driscopipe a while back. Now called Chevron Phillips Chemical.
CPC has had good design and testing info available. Contact your sales rep for the current CD or see www.

 

[tuctonyo]

I have design specs and construction data from a 16" HDPE x 7 mile long force main completed in 1995. Several factors influenced the methods, scope and frequency of testing required. State DEQ regulations governed a large part of the framework of the testing and I'm certain that those regs have been expanded and modified significantly since that time. Driscopipe was a key player and should be a prime source of curent pracitce experience.

Some of the elements that come to mind are:

Training and experience certifications for the "welder" were required to be documented and verified current through project closeout.

Construction observation and specific documentation were required

 

[tuctonyo]

(continued)

The inner weld "rings" were removed flush with the pipe I.D. and each was certified and documented individually.

A destructive test proceedure was prescribed involving the removal of a small section of pipe across each weld that was then clamped in a specially designed fixture and deformed in a specific manner using the hydraulics of a backhoe on site. Specifics varied dependent on the DR value of each test section. Three DR values were used as indicated by hydraulic pressure modeling done by Knetic Research Inc. in the area of water hammer protection. Each test was documented in a specific manner required by DEQ.

Other tests and inspections were performed and documented as required by DEQ and other agencies having authority. Ultimately, these were all combined to achieve DEQ certification and obtain the permits required to Commishion the system and commence operation.

I am sure the specifics have changed over the last 8 years and would also differ with respect to the athorities having jurisdiction at your location.

There are many more issues throughout the specs and documentation that might or might not apply to your project. It would not be practical to attempt to identify and address them in this forum.

Please feel free to let me know if I may be of any assistance.

Best of luck

 

[kfeng]

Thanks to all of you who responded in this thread from which I've got some very helpful information.

 

[stanier]

suggest you download AS 2566.2 from

http://www.standards.com.au.This

latest standard is world class and has all you need.

 

[Ag93]

Just a note regarding the merger of Plexco and Driscopipe, the new company's name is Performance Pipe, a division of Chevron Phillips Chemical. The new website is

http://www.performancepipe.com.

there is a lot of useful hdpe information on this site including sample specifications and the engineering manual. There is also a pressure test procedure available on the website.

 

[KRSServices]

A couple of further comments regarding the testing of HDPE. Assuming the 1035 kPa range (150 psi), evacuating all the air is very important because this material flexes so much that it is difficult to determine equilibrium otherwise. Regarding contraction, once the tempurature stabilizes, it does not contract or expand too much. What I have found, and actually measured, is that pipe laid during a nice sunny day will contract very noticably once it is buried and the soil tempurature achieves equilibrium. In fact, I have a spec that states (in a gravity situation) trimming in manholes will not occur until at least three days after bury and compaction. With waterline, joints are flanged and the pipe is allowed to contract prior to pouring of thrust blocks and/or restraining.

Air has always been the problem during testing and commissioning. KRS Services

http://www.krs-services.com