Polypropylene pipes. Characteristics, GOST, purpose

Standardization is a fundamental factor in shaping the quality of products that are manufactured by industry. Polymer communications are no exception. Their production is also regulated by state standard specifications for pipes (polypropylene, polyvinyl chloride, polyethylene and others). The regulatory documents reflect the basic requirements for products, their characteristics and technical parameters.

Categories of polypropylene products

The following product categories are distinguished:

• PN10: have thin walls, designed for cold water supply with a temperature of up to 20 ° C (possibly increasing to 45 ° C) at a pressure of 1 thousand kPa;
• PN20: universal, designed for hot pipelines with temperatures up to +80 ° C at a pressure of 2 thousand kPa;
• PN25: reinforced with aluminum foil, designed for water supply, heating up to +95 ° C at a pressure of 2500 kPa;
• sewer polypropylene communications and fittings;
• fiberglass reinforced pipes: applicable to all systems.

Polypropylene pipe is lightweight with a sufficiently high strength, maximum simplicity mountingfor which special fitting, surface smoothness, excellent hydraulic properties, resistance to mechanical stress. Armored communications are applicable in networks with very high temperatures.

GOST for polypropylene pipes for heating and water supply

Qualitative indicators and the scope of the polypropylene pipe are reflected in several regulatory documents (GOST). The main one is GOST R 52134, which entered into force in 2003.

Note! The standard regulates quality and defines the main parameters of a pipe made of various thermoplastic materials. In addition, the document contains requirements for connectors and fittings that are used in heating and water supply networks.

GOST applies to communications from polyethylene (PE, PE), polyvinyl chloride (unplasticized PVC-U and chlorinated CPVC), polybutene (PB, PB), cross-linked polyethylene (PE-C, PE-X), as well as polypropylene with its copolymers:

• homopolymer (Cyrillic / Latin: PP-G / RR-N);
• block copolymer (Latin / Cyrillic: РР-В / ПП-Б);
• random copolymer (Cyrillic / Latin: PP-R / PP-R).

GOST defines pipe dimensions, as well as indicators that determine their service life. These include:

• long durability;
• temperature and pressure values;
• margin of safety in coefficient representation.

The document contains a methodology for calculating the minimum wall thickness of a product based on the long-term strength of the material and operating conditions.The GOST for polypropylene pipes for water supply networks and heating systems provides test methods for products that allow their reliable assessment.

Polypropylene pipe for sewerage: GOST

For sewer communications and fittings, there is GOST 32414 from 2013. According to the standard, the maximum increase in the average outer diameter compared to the nominal one for pipes with a diameter of 32 to 63 mm is 0.3 mm, from 75 to 125 - 0.4 mm, 160 mm - 0.5 mm, 200 mm - 0 , 6 mm.

GOST establishes ranges of values ​​of average wall thickness for pipes of different nominal diameters. So, for products with a diameter of 32-50 mm, this value varies from 1.8 to 2.2 mm (sewer pipes of the S 16 and S 20 series), for other pipes the parameters are given in the table.

Table 1

For S 16 series, * 10-1 mm	Diameter	For S 20 series, * 10-1 mm
20-24	63 mm	18-22
23-28	75 mm	19-23
25-30	80 mm	20-24
28-33	90 mm	22-27
32-38	100 mm	25-30
34-40	110 mm	27-32
39-45	125 mm	31-37
49-56	160 mm	39-45
62-71	200 mm	49-56

 

If polypropylene products for sewage networks are made with a bevel, then its angle should be 15-45 degrees to the axis of the pipe. The maximum deviation of the length of the communications up or down is not more than 10 mm.

Requirements for polypropylene products according to GOST R 52134

According to GOST, for polypropylene pipes for heating or water supply to products, there are such general requirements:

• round cross section;
• attribution to pressure type;
• application in production, in residential and non-residential buildings;
• the possibility of transporting coolant, industrial and drinking water.

In addition, both the outer and inner surfaces of the pipe must be absolutely smooth with an allowable presence of longitudinal stripes and waves that do not affect the overall diameter. It is also necessary that the color of the water supply or heating communications be uniform without impurities, stripes, streaks and cracks. The color of the communications is indicated in the product regulatory document.

Note! According to GOST, polypropylene pipes can be produced with diameters of 1-160 cm.

If the outer diameter is up to 16 cm, then they are delivered in bays, wound on a spool or in the form of straight sections. Pipes with a diameter of 18 cm and above are produced in straight sections, the length of which is up to 24 meters.

Sizes of water pipes

GOST for polypropylene communications for water supply (or heating) contains requirements for their wall thicknesses. Values ​​depend on size ratio and pipe series. The change in nominal thickness, starting from ≥ 2.1 and ending with a value of ≥ 61.1, occurs in increments of 1.0. The step of increasing the value of the maximum deviation for the wall thickness of the products is 0.1, starting from 0.5. For a nominal wall thickness of ≥ 1.0, the maximum deviation is 0.4.

During testing, water pipes are maintained for at least 2 hours at a temperature of 23 ° C (with a permissible deviation in one direction or another of 5 ° C). The average outer diameter is determined at a distance of not less than 10 cm from the pipe end of the product with an error of not more than 0.05 mm. It is permissible to define this parameter as the arithmetic mean of four measurements that are uniformly distributed around the circumference of the pipe in one section and rounded to 0.1 mm.

The ovality of the communications of the polypropylene pipe (GOST 52134) is set as the subtraction of the minimum value of the external diameter of the cross section of the communications from the maximum. The wall thickness is at a distance of at least 1 cm from the end face in a single section at six points that are evenly distributed over it. The error is not more than 0.05 mm.

Testing pipes and fittings

Checking pipe resistance at constant internal pressure is carried out under the conditions presented in the table.

table 2

Temperature in ° C	20	95
Polypropylene pipe of a certain type	Initial stress in the tube wall in MPa
PP-R	16	4,2	3,8	3,5
PP-B	16	3,4	3,0	2,6
PP-N	21	5,0	4,2	3,5
Test time, h	not less than 1	not less than 22	not less than 165	not less than 1000

 

Thermal stability at a temperature of 110 ° C and is 8760 hours at values ​​of initial stress in the wall:

• for PP-R: 1.9 MPa;
• for PP-B: 1.4 MPa;
• for PP-N: 1.95 MPa.

The change in the length of the communications during heating should not exceed 2%. Tests are carried out under the conditions specified in table No. 2.

Table 3

Product type	Temperature in ° C	Time in minutes	Wall thickness in millimeters
PP-N and PP-B	150 (deviation ± 2)	240 (± 5 deviation)	over 16
		120 (± 2 deviation)	8-16
PP-R	135 (± 2 deviation)
		60 (± 2 deviation)	less than 8

 

The standard sets the value of elongation at break, which for polypropylene products of all types is at least 200%.

Note! The change in the MFI of the pipes in comparison with a similar value of the starting material should be no more than 30%, the opacity - less than 0.2%.

According to GOST, polypropylene fittings are of several types. In general, polymer elements are divided into compression, press, flange, and threaded (with elastic seals).

Technical requirements for sewer communications in accordance with GOST

Polypropylene pipe (sewer) according to document 32414 should have the characteristics that are listed in the table.

Table 4

Index	unit of measurement	Value
Impact strength (for PP at a temperature of 0 ° C, for PP-N - 23 ° C)	TIR≤10%	TIR ≤ 10%
Impact strength for polypropylene copolymer at 0 ° С (step method)	H50≥1 m (not more than 1 destruction when the load falls from a height ≤50m)	Н50 ≥ 1 m (not more than 1 destruction when the load falls from a height ≤ 50 cm)
Impact Strength (Charpy)	no more than 10	%
Changing the length of communications for sewage after heating	no more than 2	%
Change PTR - melt flow rate	no more than 0.2	g / 10 min

 

Fittings and other shaped elements must provide a waterproof connection without leaks at a pressure of 0.5 MPa for a quarter of an hour, at 0.1 MPa - for 5 minutes. Inspection of products is also carried out under the cyclic action of elevated temperatures. So, the deflection of communications for sewers with a diameter of ≤ 50 millimeters should be no more than 3 mm, and for pipes> 50 millimeters - no more than 5% of the diameter of the product.

Parameters of fittings in accordance with the standard

GOST 32414 defines the requirements for the sizes of shaped elements for sewage. These include:

• elbow (bell-bell, pipe end-bell, bent with a certain radius and welded from pipe sections);
• tee (bell-bell-bell, pipe end-bell-bell, bent with a certain radius);
• a cross (ordinary, two-plane);
• adapter pipe;
• coupling (sliding, two-bell-shaped);
• revisions;
• butt pipe for welding;
• stub.

The corners of the elements for sewage can correspond to the values ​​from table No. 4.

Table 5

Angle	Challenge	Tee	Spider
87,5-90°	+	+	+
67,5°	+	+	+
45°	+	+	+
30°	+	—	—
22,5°	+	—	—
15°	+	—	—

 

The document allows reducing the wall thickness of the pipe end or the casing to 5% with the condition that the arithmetic average of these parameters for opposite walls will be no less than the values ​​given in GOST.

note! Transitional fittings are designed for joining pipelines with different sizes. In this case, a smooth change in the wall thickness is structurally provided.

For prefabricated shaped elements, in addition to sockets and pipe ends, this change can be local in nature and be performed in the manufacture of the product.

Marking and raw material requirements for sewage products

Shaped elements, pipes and fittings are made of polypropylene block copolymer or polypropylene homopolymer with the inclusion of additives (stabilizers, pigments). The MFI value at 230 ° C / 2.16 kg should be less than 3.0 g / 10 min.

The material of shaped elements and pipes for butt welding is subject to classification according to PTR:

1. Melt Flow ≤ 0.1 g / 10 min - Class A;
2. From 0.3 g / 10 min to 0.6 g / 10 min - class B;
3. From 0.6 g / 10 min to 0.9 g / 10 min - class C;
4. From 0.9 g / 10 min to 1.5 g / 10 min - class D.

In this butt welding, sewer pipes and fittings that belong to one or the neighboring class of PTR are subject. Recyclable material may be added during production.. For the manufacture of o-rings, rubber is used.

Pipes and fittings are marked on the outside. If the thermal stamping method is used for this, then a restriction of 0.25 mm is imposed on the depth of the indentation. Marking of sewer pipes is carried out with an interval of 1 meter or less. It contains information about the manufacturer (trademark or name), the symbol of the product and the date of manufacture.

If the communications have a length of at least one meter, then they can be marked with labels, stickers. On butt welding products, a class for PTR is given.

Armored communications for heating

At heating device special attention must be paid to reinforced polypropylene pipes. GOST R 52134 determines the thickness of the products, which leads to the need to optimize the content of additives (when reinforcing with fiberglass). For this, it is necessary to take into account that the fiber of the inner layer should not violate hygiene standards and not impair the reliability of the welding joint.

Note! Fiberglass-reinforced communications are monolithic, have low thermal expansion and increased rigidity, which allows their use with smaller diameters.

The use of aluminum foil can be carried out in several ways:

• placement in the middle of the pipe wall;
• placement near the outer surface and gluing;
• the use of perforated foil in the middle of the pipe wall.

The latter method allows to obtain a monolithic compound with a polymer, which improves the parameters of the finished product. When using non-perforated foil, the structure has a multilayer structure.

Polypropylene communications are an excellent alternative to metal ones due to their high strength and operational characteristics. The use of reinforcement gives the pipes qualities that allow them to be effectively included in heating pipelines.