Procobre Perú - Publications

SUMMARY OF PERUVIAN TECHNICAL NORMS
FOR SEAMLESS COPPER ROUND PIPES FOR WATER AND GAS,
AS WELL AS ITS NORMS FOR TESTS

On June 9, 1999, the Technical and Commercial Regulations' Commission of the Institute for the Defense of Competition and Intellectual Property (Instituto de Defensa de la Competencia y de la Propiedad Intelectual - INDECOPI) as Peruvian Standardization Entity created the Permanent Technical Committee of Copper and its Alloys, Pipes and Copper Accessories Sub-committee. PROCOBRE PERU was appointed as the Committee's Secretary and entrusted on the preparation of the Projects of Peruvian Technical Norms (Proyectos de Normas Técnicas Peruanas - PNTP) related to copper and its alloys.

The Committee prepared eight Projects of Peruvian Technical Norms, which were approved by INDECOPI's Technical and Commercial Regulations' Commission as Peruvian Technical Norms. The Resolutions were published in the Official Gazette "El Peruano", five of them by Resolution N° 0070:2000/INDECOPI-CRT of November 9, 2000 and the remaining three by Resolution N° 0076:2000/INDECOPI-CRT of November 30, 2000.

The purpose of this manual is to make available to the public a summary of the Peruvian Technical Norms related to copper pipes, a product with broad application in construction and industry that can be used in fresh water, gas and liquid fuel distribution, cooling, heating and domestic sewage evacuation installations. In addition, to motivate readers to review all the norms that will be available at INDECOPI's Information Center and main libraries of the country.

Our gratitude to institutions, and companies and their representatives that participated actively and contributed with their experience in the preparation of the eight norms related to copper pipes.

COMMITTEE MEMBERS:

SECRETARY

PROCOBRE PERU

PRODUCTION SECTOR

F EBERHARDT S.A., OSCAR BARRENECHEA REPRESENTACIONES, ACERSA, TECNOFIL S.A.

CONSUMPTION SECTOR

MINISTRY OF ENERGY AND MINES - GENERAL DIRECTION OF HYDROCARBONS REPSOL YPF COMERCIAL DEL PERU MINISTRY OF TRANSPORTATION, COMMUNICATIONS, HOUSING AND CONSTRUCTION --VICEMINISTRY OF HOUSING AND CONSTRUCTION PERUVIAN CHAMBER OF CONSTRUCTION MINISTRY OF INDUSTRY, TOURISM, INTEGRATION AND INTERNATIONAL COMMERCIAL NEGOTIATIONS - NATIONAL DIRECTION OF INDUSTRIES

TECHNICAL SECTOR

SCHOOL OF ENGINEERS OF PERU - CIVIL ENGINEERING CHAPTER MAJOR NATIONAL UNIVERSITY SAN MARCOS - FACULTY OF MECHANICAL ENGINEERING MAJOR NATIONAL UNIVERSITY SAN MARCOS - FACULTY OF ENVIRONMENTAL ENGINEERING CATHOLIC UNIVERSITY OF PERU - MECHANICAL ENGINEERING SECTION NATIONAL TRAINING SERVICE FOR THE CONSTRUCTION INDUSTRY (SENCICO) NATIONAL TRAINING SERVICE ON INDUSTRIAL WORK (SENATI) TECHNOLOGICAL SUPERIOR INSTITUTE (TECSUP)

PERUVIAN TECHNICAL NORMS PREPARED BY THE COMMITTEE

NTP 342.052:2000 COPPER AND COPPER ALLOYS. Seamless copper round pipes for water and gas.

NTP 342.520:2000 COPPER AND COPPER ALLOYS. Combustion method to determine carbon on the inside surface of pipes and copper pipes accessories.

NTP 342.521:2000 COPPER AND COPPER ALLOYS. Test Method of induced currents for pipes.

NTP-ISO 8491:2000 METALLIC MATERIALS. Pipes (in full circular section). Bending test.

NTP-ISO 8493:2000 METALLIC MATERIALS. Pipes. Conical countersunk test.

NTP-ISO 8494:2000 METALLIC MATERIALS. Pipes. Flat countersunk (flanged) test.

NTP-ISO 6507-1:2000 METALLIC MATERIALS. Vickers hardness test method.

NTP-ISO 6892:2000 METALLIC MATERIALS. Room temperature tension test.

NTP 342.052:2000 SEAMLESS COPPER ROUND PIPES FOR WATER AND GAS

OBJECTIVE AND FIELD OF APPLICATION

Requirements, sample tanking, test methods and supply conditions for copper pipes are established.

It is applied to seamless round copper pipes with exterior diameter between 6mm and 308 mm inclusive, used in:

Hot or cold water distribution networks;
Gas and liquid fuel distribution networks;
Heating system with hot water, including the heating systems by radiant soil;
Domestic sewage evacuation.

DEFINITIONS

The necessary definitions for the product are established, such as:

Seamless round copper pipe: A semifinished product copper-made, hollow, circular transverse section and uniform nominal depth wall, which has a continuous perimeter supplied as straight manufactured panels or rolls.

Additionally, other definitions are presented that may be applied to operations of joining pipes with its accessories, such as capillary welding, soft welding, brazing, non-capillary welding, fusion welding; the production lot is defined for sampling and those referred to characteristics of pipes, such as: mean diameter, ovalization, eccentricity and temper or treatment condition. .

REQUIREMENTS AND TEST METHODS

Minimum requirements as well as the corresponding test method for the product are established as follows::

Composition: Cu + Ag: min 99,90%; 0,015%= P = 0,040%.
Mechanical properties: resistance to traction, stretching and harness.
Dimensions and tolerances: exterior diameter, wall thickness and length.
Absence of defects: tests for induced currents, hydrostatic pressure, and pneumatic pressure.
Surface quality: interior and exterior surfaces, flat and clean, having the option to determine the carbon content and carbonaceous film.
Bent: the test tube should bend at 90° angle with a minimum curvature radius.
Conical countersunk: with a 45° angle.
Flat countersunk (flanged): until a flange perpendicular to the pipe shaft is obtained.

SURVEY AND SAMPLING

NTP established where to carry out the survey, how to consider lots, lot's mass, number of sample units, which shall be randomly taken from each lot, and finally, the acceptance and rejection.

DESIGNATION AND SPECIFICATION FOR ORDERS

NTP indicates the material designation, the temper or treatment condition and the product.

Minimum specifications required are established to facilitate the request, order and order confirmation between buyer and vendor

NTP 342.520:2000 COMBUSTION METHOD TO DETERMINE THE CONTENT OF CARBON ON THE INTERIOR SURFACE OF COPPER PIPES AND ITS ACCESSORIES

OBJECTIVE AND FIELD OF APPLICATION

A combustion method to determine the content of carbon on the interior surface of copper pipes and its accessories is established in the Peruvian Technical Norm.

The Peruvian Technical Norm can only be applied to copper round pipes established in NTP 342.052 and to copper pipes' accessories established in the respective NTPs whenever required prior agreement between the buyer and the supplier or manufacturer.

DEFINITIONS

Determinations to be carried out are establishes, such as residual carbon, potential carbon and total carbon.

GENERAL PRINCIPLE

Carbon combustion on the interior surface of a pipe or accessory sample is carried out at a specific temperature in an oxygen current. The content of carbon is expressed in terms of total, residual or potential carbon.

The Norm describes a combustion method and three measurement methods for produced carbon dioxide. The content of residual carbon, total carbon or both is determined.

Potential carbon is determined by calculation (total carbon minus residual carbon).

SAMPLE PREPARATION

The sequence of operations to carry out in order to determine the carbon is established, which include sample taking in case of pipes or its accessories, cleaning of sample's interior and external surface. Cleaning may be chemical or mechanical and test tube cut be it in pipes or accessories.

COMBUSTION METHOD IN PRODUCTS CONTAINING CARBON

It is established that combustion should be carried out in a quartz pipe through which circulates an oxygen current with purity higher than 99,995% and the detailed composition of the combustion device is indicated as from the oxygen connection

METHODS TO DETERMINE THE CONTENT OF CARBON

Three basic methods to determine the content of carbon are described as follows:

Tetrabuthylammonium hydroxide (HTBA) method;
Measurement of differential electric conductivity determination method;
Infrared absorption spectrometry determination method

The procedure for target determination necessary for each method is also described..

TEST REPORT

The NTP establishes issuing a Test Report including the list of indications it shall contain.

Whatever test method is used, the value of the carbon content should be expressed in mg/dm2, considering the arithmetic mean of obtained values in two test tubes. .

NTP 342.521:2000 TEST METHOD OF INDUCED CURRENTS FOR PIPES

OBJETIVE

The Peruvian Technical Norm establishes a procedure for testing with induced currents of copper seamless round pipes and copper alloys.

Its objective is to detect potential leak points and significant defects during the manufacturing process of pipes. The test method or methods of induced currents needed together with the size range and level of acceptance are defined in the corresponding norm of the product.

DEFINITIONS

Definitions to consider are included in the European Norm UNE-EN 1330-5.

METHOD SUMMARY

This test is generally carried out by putting the pipe longitudinally through an excited coil with alternating current of one or more frequencies. The pipe's proximity, dimensions, electric conductivity and the material's magnetic permeability and metallurgic or mechanical discontinuities alter the coil's electric impedance.

While the pipe is put through the coil, changes in the electromagnetic responses caused by these variables on the pipe generate electric signals that are processed and recorded, and may activate devices of auditory or visual signals or mechanical marks.

SIGNIFICANCE AND USE

The test of induced currents is a non-destructive method used to determine discontinuities in a product. The signals may be produced by discontinuities located indistinctly onto pipe's exterior or interior surfaces or by discontinuities totally contained within them.

With respect to signals obtained during the test, the NTP provides several warnings that should be taken into account so incorrect rejections or acceptances are not made. Therefore, they are considered as doubtful signals that require verification through another inspection or test method.

It is mentioned that the test usually is non-sensitive for adjacent discontinuities to the pipe's edges (edges' effect) and that discontinuities such as scratches or seams that are continuous and uniform along the pipe's length may be difficult to detect.

GENERAL REQUIREMENTS

Skills of personnel in charge of the test as well as its certification according to Norms in effect is considered as the condition to carry out a pipe test without difficulties in the corresponding equipment.

Several conditions are established for the equipment that will be used in the tests, which shall be complied while conducing the pipe through the test coils, the variation maintenance of sensibility in a range, the alternative to use a circular coil system (see figure) or the system that consists in a relative rotation movement between the pipe and one or several calipers (superficial sensor) (see figure). It also considers the test velocity, the precaution to keep the caliper at a certain distance from the pipe's external surface to that the test sensibility be adequate.

bobina secundaria
bobina primaria
tubo

Representación esquemática del control de corrientes inducidas usando bobinas circulares exteriores (pueden ser primarias, secundarias, absolutas).

Palpadores (sensores de superficie) rotando con movimiento lineal del tubo Tubo rotando con movimiento lineal del palpador

Representación esquemática de un sistema de corrientes inducidas, que involucra un movimiento relativo de rotación entre el tubo y el palpador (control helicoidal del tubo).

NOTA : El palpador (sensor superficial) puede tener diferentes formas, por ejemplo en bobinas simples o bobinas múltiples con varias configuraciones.

REFERENCE GUIDE PIPE

NTP establishes the characteristics required for the reference guide pipe, defect-free, with the same dimensions and specified characteristics for testing, location of holes or holes (one or three), spacing and equidistance to obtain signals without interference.

ACCEPTANCE CRITERIA

NTP establishes the acceptance criteria in detecting punctual discontinuities through the circular coil system, as well as in the case of detecting non-punctual discontinuities through the exterior circular coil with lower detection levels. A method is established for this purpose, as well as the total length to be considered defective.

INSTRUMENT REGULATION

The NTP establishes the actions to carry out and information to consider when regulating test equipment.

NTP-ISO 8491:2000 PIPES (COMPLETE CIRCULAR SECTION). BENT TEST

OBJECTIVE AND FIELD OF APPLICATION

The Peruvian Technical Norm establishes a method to determine the capability to plastic deformation by bent of a part of metallic pipe with circular section.

The method can be used in pipes with exterior diameter equal or less than 65 mm, although the range of exterior diameters to which the Peruvian Technical Norm is utilized may remain defined more explicitly in the corresponding norm of the product.

The bent tests of test tubes taken from pipes as transverse sides are carried out according the instructions of Norm ISO 7438:1985 so as to increase the initial curvature of the test tube.

PRINCIPLE

The test consists in the bent of a straight part of pipe over a mandrel with specified radius (f) with thoric groove until the curved angle (a) reaches the specified value in the corresponding norm of the product (see figure).

SYMBOLS, DESIGNATION AND UNITS

Symbols for the bent test

Symbol	Designation	Unit
D e L r a	Exterior diameter of pipe Pipe's wall thickness Length of the test tube before the test Interior radius of the mandrel at the bottom of the groove Bent angle	mm mm mm mm ° (degrees)

OPERATIVE PROCEDURE

The NTP establishes a test equipment considering the parts that produce the pre-established structure indicating dimensions, geometric characteristics and material finishing. It also establishes the preparation in dimensions and the structure of the test tube.

The test interpretation is made according to the corresponding norm of the product or verifying if the test tube has no visible fissures without using an amplification method. A slight fissure onto the edges shall not be considered as a cause to rejection.

A test report should be issued in case the corresponding norm of the product established it so. The NTP establishes the list of instructions to be included in the Test Report.

Conditions: it is established the room temperature conditions to carry out the test, the conformation process of the test tube through a mandrel of the equipment with thoric groove until reaching the specified a angle and precautions to take into account during the test.

NTP-ISO 8493:2000 PIPES. CONICAL COUNTERSUNK TEST

OBJECTIVE AND FIELD OF APPLICATION

The Peruvian Technical Norm establishes a method to determine the capability to plastic deformation by conical countersunk of metallic pipes with circular section.

The Norm is used in pipes with exterior diameter lower than 150 mm (100 mm for light metals) and wall thickness lower than 10 mm. The range of exterior diameters or thickness to which the Peruvian Technical Norm is adjusted, would remain defined more explicitly in the corresponding norm of the product.

PRINCIPLE

The test consists to widen the edge of a test tube cut from a pipe with the assistance of a mandrel in the form of a truncated cone until the maximum exterior diameter of the pipe countersunk this way reaches the specified value in the respective norm of the product (see figure).

Symbol for the conical countersunk test

Symbol	Designation	Unit
D e L D_u ß	Exterior diameter of the pipe Wall thickness of the pipe Test tube length before the test Maximum exterior diameter of the conical countersunk Mandrel cone angle	mm mm mm mm ° (degrees)

OPERATIVE PROCEDURE

It is similar to the summary described in norm NTP-ISO 8491:2000 OPERATIVE PROCEDURE but with different conditions for the test as follows:

Conditions: It is established the room temperature to carry out the test, the conformation process of the test tube through the equipment's mandrel until reaching a maximum exterior diameter of the test tube's countersunk part, the precautions that should be taken into account during the test and the penetration velocity.

NTP-ISO 8494:2000 PIPES. FLAT COUNTERSUNK TEST (FLANGED)

OBJECTIVE AND FIELD OF APPLICATION

The Peruvian Technical Norm establishes a method to determine the capability to plastic deformation for countersunk until bent making a flange in the metallic tubes with circular section.

The Norm can be used in pipes with exterior diameter lower than 150 mm and with wall thickness lower than 10 mm. The range of exterior diameters or wall thickness to which the Peruvian Technical Norm can be used may be described more explicitly in the corresponding product norm.

PRINCIPLE

The consists of making a flange that is perpendicular to the pipes axis onto the edge of a trimmed test tube of a pipe until the exterior diameter of the flange reaches the value established in the corresponding product norm.

Symbols for the flat countersunk test (flanged)

Symbol	Designation	Unit
D e L r D_u ß	Exterior diameter of the pipe Wall thickness of the pipe Test tube length before the test Curvature radius of the tool it's deforming Maximum exterior diameter of the flat countersunk Angle of the mandrel's cone	mm mm mm mm mm ° (degrees)

OPERATIVE PROCEDURE

It is similar to the summary described in norm NTP-ISO 8491:2000 OPERATIVE PROCEDURE but with different conditions for the test as follows:

Conditions: It is established the room temperature to carry out the test, the conformation process of the test tube through the equipment's mandrel until making the final flange, the precautions that should be taken into account during the test and the penetration velocity:

NTP-ISO 6507-1:2000 VICKERS TENSILE TEST METHOD

OBJETIVE

The Peruvian Technical Norm establishes the Vickers tensile test method for three different test force ranges used in metallic materials (see chart).

Test force range, F in newton (N)	Tensile symbol	Prior designation (ISO 6507-1:1982)
F ³ 49,03	³ HV5	Vickers tensile test
1,961 £ F < 49,03	HV 0,2 a < HV 5	Vickers tensile test with low force
0,09807 £ F <1,961	HV 0,01 a < HV 0,2	Vickers microtensile test

The Vickers tensile test established in the Peruvian Technical Norm is used for length indentation diagonals between 0,020 mm and 1,400 mm.

PRINCIPLE

A diamond normalized penetrator with straight pyramidal shape with squared base and specified angle between two opposed sides to the vortex is forced against the surface of a test part followed by the length measurement of indentation diagonals left in the surface after removing the test force, F (see figure).

a) Indentator (diamond pyramid)
b) Vickers indentation track

Vickers tensile is proportional to the quotient resulting from the division of the test force between the surface area of indentation, which it is assumed that corresponds to a straight pyramid with squared base and the vortex in the same angle as the indentator.

SYMBOLS AND DESIGNATIONS

Symbol	Designation
a	Angle between the two opposite sides of the vortex of the pyramid indentator (136°)
F	Test force, in newton (N)
d	Arithmetic media of the length of two diagonals d1 and d2 in millimeters (see figure b), Vickers indentation track)
HV
NOTE: Constant = 1/gn = 1/9,80665 » 0,102 where: gn is the constant for gravity

The designation of the Vickers tensile is with the symbol HV preceded by the tensile value and followed by:

a) A number representing the test force.

b) The time of the charge in seconds, in case a different time to that specified in the NTP as normal time has been used.

PROCEDURE

The NTP established the reference of the test machine, the indentator and the measurement device in accordance to International Norm ISO 6507-2.

For the test part, it is established the preparation of the surface, precautions to avoid tensile alterations, considerations on the thickness of the part and special mention for the application of the corrections provided in the charts included in the NTP for curve surfaces -which is the case of pipes.

In the procedure, there are established the room temperature conditions to carry out the test, the test forces that must be used, the process from the firm installation of the part to test, the application of the indentator until reaching the specified force value and the time of application of the force, the application distances of indentations with respect to the part's edges and the distances between the indentation centers, and finally, the length measurement of diagonals for the tensile calculation.

The NTP establishes to provide a Test Report and indicates the list of instructions said report must include. .

CHART OF CORRECTION FACTORS TO BE USED IN TESTS MADE ON CURVE SURFACES

For cylindrical surfaces, the NTP includes several charts that show the correction factors to determine the tensile as well as examples for calculations..

NTP-ISO 6892:2000 TRACTION TEST AT ROOM TEMPERATURE

OBJECTIVE

The Peruvian Technical Norm establishes the traction test method at room temperature for metallic materials and defines the mechanical properties that may be determined with this test.

METHOD'S PRINCIPLE

The test consists of making a test tube subject to a traction effort, generally until breakage, to determine one or several characteristics established in chapter 4 of said Norm.

Excepting any instruction on the contrary, the test is carried out at room temperature that is between 10°C and 35°C. For tests that must be carried out under controlled conditions, the room temperature should be kept at (23 +/- 5)°C.

DEFINITIONS

All the characteristics shown during the traction test are defined, from those that need to prepare test tubes for the test to those that establish the mechanical properties to be determined.

SYMBOLS AND DESIGNATIONS

A chart of the NTP includes the description for 29 designations, 24 of which are mentions with symbols and 28 with reference numbers. In addition, 13 figures are used to help understanding of the mechanical properties and the test tubes that will be used.

TEST TUBES

It is established the shape and dimensions of the test tubes, the types and preparation of the same, how to determine de area from the initial section and the detail of the initial length between marks.

CONDITIONS FOR A TEST

It is provided all instructions depending on the nature of the product, the velocity of the machine as well as the fastening methods. The precision of the test devices is also mentioned.

DETERMINATION OF MECHANICAL PROPERTIES

It is established the procedures to determine the following:

Stretching percentage after breakage
Total stretching percentage at maximum force
Conventional elastic limit
Elastic limit for total extension
Area reduction percentage (striction)

TEST REPORT

A report is provided to show the information it should include.

ANNEXES

NTP includes twelve annexes, among which Annex D describes the type of test tubes for pipes, mentioning shape and dimensions in case of a complete pipe and when the pipe has longitudinal or transverse sides. Likewise, formulae for calculations are included in case of making it circulate with mechanic means, from the pipe's wall and the determination of the area of the initial section (So). This annex refers to the following figures

A piece of pipe as test tube

Meaning of numbers in the figure:

1. Wall thickness of a pipe.
2. Mean width of the longitudinal side taken from a pipe.
3. Exterior diameter of a pipe.
4. Initial longitude between marks.
5. Longitude of the calipered part.
6. Total longitude of the test tube.
7. Final longitude between marks.
8. Area of the inicial section of the calipered part.
9. Minimum area of the section after breaking.
10. Edge for clamp (mooring edge).

Test tubes cut from a pipe