Polyethylene products. Characteristics of the pipe in accordance with GOST

Polyethylene products are used for pipelines for various purposes. Technical and operational characteristics allow the use of PE products for laying cables and power lines, transporting gas and liquids. Polyethylene communications have proven themselves in the installation of sewers, drainage systems and pressure pipes. The parameters and properties of the pipe are regulated by GOST.

The use of plastic products

There are pipes made of polyethylene (P) high (B) and low (H) pressures (D). LDPE products have a limited area of ​​use. Typically, pipelines for drinking water or other liquid media are built on their basis. LDPE pipes can be laid in the ground without the use of additional shells for protection.

High hardness, density, low combustibility, flammability, and dielectric properties of HDPE pipes make it possible to take them as the basis of sewer systems, water pipelines (both drinking and industrial water), gas pipelines, industrial pipelines, for laying cables and wiring elements.

LDPE is performed at elevated pressure. Its melting point is about 110 degrees. Gas and moisture permeability of PND products is five times less than LDPE. They are great for outdoor piping.

Overview of GOSTs on PE pipe

There are several standards (GOSTs) for polyethylene pipes. Each document defines the main characteristics, features, assortment and other important properties of products. So, we can distinguish GOST 18599, GOST 22689, GOST 32415, GOST 50838. The properties of PE as a material are prescribed in standard 16338, approved in 1985.

Document 18599-2001 applies to pressure pipeswhich are divided into 3 types:

1. PE products with possible presence of marking strips.
2. PE pipes having coextrusion layers of the same MRS level (minimum - "minimum", required - "long", strength - "strength") inside and / or outside.
3. Polyethylene products with a protective shell made of thermoplastic.

GOST 22689, approved in 2014, establishes the technical parameters of shaped elements and PE pipes for an internal water drainage and sewage system. Document 50838 outlines the requirements for PE pipes for transporting gas, which is used as fuel and raw material in industry or municipal services.

Note! According to the standard 18599, products for laying cables are produced.

GOST 32415 was approved in 2013 and applies to thermoplastic products, including polyethylene, pressure type for heating, cold water supply and connecting elements (fitting) to them.

Characteristics of PE (GOST 16338)

Regulatory document 16338 regulates the technical performance of HDPE (high density), which is obtained by gas-phase or suspension method of ethylene polymerization (C₂N₄) at low pressures.

Also indicated are compositions and brands of PE permitted for the production of products in contact with drinking water, food, pharmaceuticals and cosmetics, and other purposes. Pipes and films should be made of gas-phase compositions of the first and highest grades or suspension - of the second and first grades.

The document sets the maximum concentration of harmful substances that can be released into food, water or air. The corresponding values ​​are given in the table.

Table 1

Product name	Permissible concentration, mcg / m3	Hazard class (GOST 12.1.007)
Formaldehyde	500	2
Acetaldehyde	5 thousand	3
Carbon monoxide	20 thousand	4
Organic acids (converted to acetic acid)	5 thousand	3
Aerosol PE	10 thousand	3

 

HDPE (according to GOST 16338) is a combustible material. At room temperature, it does not emit harmful substances into the environment. During processing, when values ​​exceed 140 degrees, volatile products that contain organic acids may be released.

HDPE pipe production

GOSTs on polyethylene products for cables, water supply, sewage, gas, regulate not only the technological process for the production of semi-finished HDPE, but also pipes. So, according to the standard 18599, there are two ways to obtain the final product:

• extrusion;
• casting.

By extrusion is meant extrusion of a pipe from granules in a molten state. The product obtains the required shape thanks to the extruder head. In this case, the superheated polymer is pushed by the press.

The pipe is obtained by casting using a rotating mold, to the walls of which molten material sticks.

Note! This process is more complicated than extrusion, but it is possible to obtain more accurate HDPE pipes with minimal deviations and ovality.

There is another way to get the pipe - pneumatic formation. In this case, the polymer is fed into the mold under pneumatic pressure, as a result of which a PND product is formed.

Depending on the selected type of production and raw material features, you can get the final product with various technical characteristics. HDPE pipes, GOSTs that regulate their parameters, specific application conditions - all these are important issues that require special attention when it is necessary to equip a pipeline for gas, water, cables, etc.

PE pipe dimensions as per document 32415

GOST for pipes (polyethylene) for water supply determines the main dimensions of the products. The corresponding values ​​from the standard are given in the table. SDR (СРО) - standard ("standard") dimensional ("dimension") relation ("ratio").

table 2

Polyethylene grade	80	80, 100
	Series 2.5; SRO 6	Series 3.2; SRO 7.4	Series 4; SRO 9	Series 5; CPO 11	6.3 series; SRO 13.6	Series 8; CPO 17	Series 10; SRO 21	Series 12.5; SRO 26	Series 16; SRO 33	Series 20; CPO 41
Diameter, * 103 mm	Pipe wall, * 10-1mm
0,016	30	23	20	—	—	—	—	—	—	—
0,020	34	30	23	20	—	—	—	—	—	—
0,025	42	35	30	23	20	—	—	—	—	—
0,032	54	44	36	30	24	20	—	—	—	—
0,040	67	55	45	37	30	24	20	—	—	—
0,050	83	69	56	46	37	30	24	20	—	—
0,063	105	86	71	58	47	38	30	25	—	—
0,075	125	103	84	68	56	45	36	29	—	—
0,090	150	123	101	82	67	54	43	35	—	—
0,110	183	151	123	100	81	66	53	42	—	—
0,125	208	171	140	114	92	74	60	48	—	—
0,140	233	192	157	127	103	83	67	54	—	—
0,160	266	219	179	146	118	95	77	62	—	—
0,180	299	246	201	164	133	107	86	69	—	—
0,200	332	274	224	182	147	119	96	77	—	—
0,225	374	308	252	205	166	134	108	86	—	—
0,250	415	342	279	227	184	148	119	96	—	—
0,280	465	383	313	254	206	166	134	107	—	—
0,315	523	431	352	286	232	187	150	121	97	77
0,355	590	485	397	322	261	211	169	136	109	87
0,400	665	547	447	363	294	237	191	153	123	98
0,450	—	615	503	409	331	267	215	172	138	110
0,500	—	683	558	454	368	297	239	191	153	123
0,560	—	—	625	508	412	332	267	214	172	137
0,630	—	—	—	572	463	374	300	241	193	154
0,710	—	—	—	645	522	421	339	272	218	174
0,800	—	—	—	—	588	474	381	306	245	196
0,900	—	—	—	—	662	533	429	344	276	220
1,000	—	—	—	—	725	593	477	382	306	245
1,200	—	—	—	—	882	679	572	459	367	294
1,400	—	—	—	—	1029	824	667	535	429	343
1,600	—	—	—	—	1176	941	762	612	490	392

 

Limit deviations in the size of polyethylene pipes

GOST 32415 establishes the permissible diameter deviations and ovality of PE products.

Table 3

Diameter, * 1 thousand mm	Tolerance upward, * 10-1mm	Ovality mm * 10-2 not more
0,016	3	120
0,020	3	120
0,025	3	120
0,032	3	130
0,040	4	140
0,050	4	140
0,063	4	150
0,075	5	160
0,090	6	180
0,110	7	220
0,125	8	250
0,140	9	280
0,160	10	320
0,180	11	360
0,200	12	400
0,225	14	450
0,250	15	500
0,280	17	980
0,315	19	1110
0,355	22	1250
0,400	24	1400
0,450	27	1560
0,500	30	1750
0,560	34	1960
0,630	38	2210
0,710	64	—
0,800	72	—
0,900	81	—
1,000	90	—
1,200	108	—
1,400	126	—
1,600	144	—

 

For the wall thickness of a PE pipe, GOST provides such data (in millimeters).

Table 4

Pipe wall made of polyethylene, * 10-1		Variation upward in grade V
>	≤
10	20	0,3
20	30	0,4
30	40	0,5
40	50	0,6
50	60	0,7
60	70	0,8
70	80	0,9
80	90	1,0
90	100	1,1
100	110	1,2
110	120	1,3
120	130	1,4
130	140	1,5
140	150	1,6
150	160	1,7
160	170	1,8
170	180	1,9
180	190	2,0
190	200	2,1
200	210	2,2
210	220	2,3
220	230	2,4
230	240	2,5
240	250	2,6
250	260	2,7
260	270	2,8
270	280	2,9
280	290	3,0
290	300	3,1
300	310	3,2
310	320	3,3
320	330	3,4
330	340	3,5
340	350	3,6
350	360	3,7
360	370	3,8
370	380	3,9
380	390	4,0
390	400	4,1
400	410	4,2
410	420	4,3
420	420	4,4
420	440	4,5
440	450	4,6
450	460	4,7
460	470	4,8
470	480	4,9
480	490	5,0
490	500	5,1
500	510	5,2
510	520	5,3
520	530	5,4
530	540	5,5
540	550	5,6
550	560	5,7
560	570	5,8
570	580	5,9
580	590	6,0
590	600	6,1
600	610	6,2
610	620	6,3
620	630	6,4
630	640	6,5
640	650	6,6
650	660	6,7
660	670	6,8
670	680	6,9
680	690	7,0
690	700	7,1

 

Basic design ratios

According to GOST, a polyethylene pipe can be operated for 50 years at a temperature of the working environment of 20 degrees. These values ​​are inherent in cold water supply.

For him, the nominal pressure, rated voltage and series of the product are related by this ratio:

D = 10 * N / C = 10 * MRS / S * K,

where K is the safety factor in the form of a coefficient taking into account the operating conditions of the pipeline; C - a series of pipes; MRS is the minimum value of long-term strength, expressed in MPa; N is the calculated voltage (in MPa).

If the pipeline carries water whose temperature is above 20 degrees, then the value of the working pressure is adjusted by entering a coefficient. In this case, the relation

D1 = D * K1,

where D1 - allowable pressure, expressed in bar; D is the nominal pressure; K1 - pressure reduction in coefficient form, the value of which is given in the table.

Table 5

K1 value for polyethylene pipe	Water temperature, degrees
1,00	20
0,93	25
0,87	30
0,80	35
0,74	40

 

Technical requirements according to GOST 32415

Pipes should be smooth both inside and out. Fulfillment of this requirement is important to ensure a given pipeline throughput. Slight undulation and the presence of longitudinal stripes are allowed.

Note! On the surface there should not be bubbles, shells, foreign inclusions and cracks.

The resistance of pipes (GOST 32415) to internal pressure is determined during tests, the modes of which are given in the table.

Table 6

No. p / p	Test time, min., No less	Test temperature, degrees	Ring (hydrostatic) stress for the brand PE, kPa
			100	80
1	6 thousand	20	12 thousand	10 thousand
2	165*60	80	5400	4500
3	60 thousand	80	5 thousand	4 thousand

 

With plastic failure for the second mode, the tests are repeated under the conditions specified in the table.

Table 6

PE brand 100		PE brand 80
Hydrostatic stress, kPa	Time h	Time h	Hydrostatic stress, MPa
5400	165	165	4,5
5300	256	233	4,4
5200	399	331	4,3
5100	629	474	4,2
5 thousand	1 thousand	685	4,1
—	—	1 thousand	4,0

 

Water pipes can be extended after heating by a temperature of 110 ± 2 ºС by no more than 3%. The tests last 60 ± 2 minutes for products with a wall of up to 8 mm, 120 ± 2 minutes - from 8 to 16 mm and 240 ± 2 minutes - more than 16 mm. At break, the elongation of the pipe grades 80, 100 is not less than 350%. The change in PTR compared with the initial one is not more than 20 percent, thermal stability at a temperature of 200 degrees is not less than 20 minutes.

Durability parameters of pipe joints

Polyethylene pipes connected by fittings must meet the requirements of the standard. The welded joint of products and its technical parameters of resistance are checked during tests with a temperature of 80 ° C for at least 165 hours at a hydrostatic (ring) voltage of 5.4 MPa (for PE 100) and 4.5 MPa (for PE 80).

Mechanical joints of pipes made of polyethylene are checked under the conditions indicated in the table.

Table 7

Test design	Pressure bar	Temperature degrees	Test time, not less than, h
No bending PE pipe	1.5 * nominal pressure	20	1
With a bend			1

 

Mechanical joints are also subject to verification of resistance to tensile load (at a temperature of 20 degrees for at least an hour), which is calculated by the formula:

PH = 1.5 * N * π * (ND-TS) * TS,

where RN - tensile load, N; N - permissible voltage: 8 MPa (for PE 80), 10 MPa (for PE 100); ND - nominal value of the outer diameter, mm; TS - the average wall thickness, mm.

The bending radius can be 15 outside diameters of the pipe (in mm) if the nominal pressure is ≤10 and 20 outside diameters if more than 10. Nominal pressure should be selected from the table.

Table 8

Series	SDR	Nominal pressure for polyethylene grade, * 10-1
		80	100
20	41	32	40
16	33	40	50
12,5	26	50	60
10	21	60	80
8	17	80	100
6,3	13,6	100	125
5	11	125	160
4	9	160	200
3,2	7,4	200	250
2,5	6	250	—

 

If used for the connection compression fittings, then the test pressure shall correspond to the values ​​in the table (symbol: NI - nominal pressure).

Table 9

Temperature test degrees	Time, h, no less	Pressure, bar, for fittings made of
		PP-R	PP-B	PP-H	POM	ABS
20	1 thousand	1.2 * ND		1.5 * ND
40		0.8 * ND		1.1 * ND

 

Sizes of sewage products made of polyethylene

Sewer pipes (GOST 22689) are characterized by the dimensions indicated in the table.

Table 10

Nominal size, * 10-1 mm	Outer diameter (nominal) * 10 mm	The average value of the outer diameter, * 10-1 mm
		maximum	minimum
320	3,2	323	320
400	4,0	404	400
500	5,0	505	500
630	6,3	636	630
750	7,5	757	750
800	8,0	808	800
900	9,0	909	900
1 thousand	10,0	1009	1 thousand
1100	11,0	1110	1100
1250	12,5	1262	1250
1600	16,0	1615	1600
2 thousand	20,0	2018	2 thousand
2500	25,0	2523	2500
3150	31,5	3179	3150

 

The standard also sets the wall thickness.

Table 11

Outer diameter (nominal) * 10 mm	Wall, * 10-1 mm
	For 12.5 series		For series 16
	maximum	maximum	minimal	minimal
3,2	35	30	35	30
4,0
5,0
6,3
7,5
8,0	36	31
9,0	41	35
10,0	44	38	38	32
11,0	49	42	40	34
12,5	55	48	45	39
16,0	71	62	56	49
20,0	87	77	71	62
25,0	108	96	87	77
31,5	136	121	109	97

 

Other wall thicknesses of products are also acceptable at any point, but not more than 1.25 of the minimum limit.

Technical parameters of sewer pipe

A polyethylene pipe (GOST 22689) for sewage after heating can be extended by no more than 3%. In this case, the appearance of cracks or bubbles is unacceptable. Change PTR for pipes that are designed for butt welding - no more than 2 * 10^-1 g / 10 minutes.

If connection should be pipes and fittings with a sealant, then water tightness without leaks at a pressure inside 0.05 MPa should be within 15 minutes, and air tightness at a pressure of 0.01 MPa within 5 minutes. PTR indicators for products comply with GOST 11645.

Note! The document allows the addition of recycled material bearing the same brand in the composition.

HDPE pipes have a high degree of rigidity due to their crystal structure. They are characterized by high strength, density, low modulus of elasticity. The main document for a pressure head sewer pipe (PND) is GOST 18599.

Weight of polyethylene pipe for sewage

GOST 18599 establishes the mass values ​​of 1 meter of the pipeline from PE products.

Table 12

Outer Diameter * 103 mm	Mass g
	SRO - 41, series 20	SRO - 26, series 12.5	SRO - 21, series 10	SRO - 17.6, 8.3 series	SRO - 17, series 8	SRO - 13.6, 6.3 series	SRO - 11, series 5	SRO - 9, series 4	SRO - 6, series 2.5
0,010	—	—	—	—	—	—	—	—	52
0,012	—	—	—	—	—	—	—	—	65
0,016	—	—	—	—	—	—	92	92	116
0,020	—	—	—	—	—	—	118	134	182
0,025	—	—	—	151	—	151	172	201	280
0,032	—	—	197	197	197	233	280	329	459
0,040	—	249	249	286	297	358	432	511	713
0,050	—	315	376	443	456	552	669	798	1100
0,063	401	497	582	691	724	885	1060	1270	1750
0,075	480	678	831	981	1020	1250	1490	1790	2480
0,090	643	982	1190	1420	1480	1800	2150	2590	3580
0,110	946	1440	1780	2090	2190	2660	3200	3840	5340
0,125	1240	1870	2290	2690	2810	3420	4160	4960	6900
0,140	1550	2350	2890	3390	3520	4290	5190	6240	—
0,160	2010	3080	3770	4410	4600	5610	6790	8130	—
0,180	2500	3850	4730	5570	5830	7100	8590	10300	—
0,200	3090	4770	5880	6920	7180	8750	10600	12700	—
0,225	3910	5980	7450	8740	9120	11100	13400	16100	—
0,250	4890	7430	9100	10800	11200	13700	16500	19800	—
0,280	6090	9290	11500	13500	14000	17100	20700	24900	—
0,315	7630	11800	14500	17100	17800	21700	26200	31500	—
0,355	9740	14900	18400	21600	22600	27500	33300	40000	—
0,400	12300	18900	23400	27500	28600	34900	42300	50700	—
0,450	15600	23900	29600	34800	36300	44200	53600	64200	—
0,500	19300	29500	36500	42900	44800	54700	66100	79200	—
0,560	24100	37100	45800	53700	56100	68500	82800	—	—
0,630	30500	47000	57800	68100	71200	86688	104800	—	—
0,710	38800	59700	73600	86400	90300	110000	—	—	—
0,800	49300	75600	93300	109700	114500	139700	—	—	—
0,900	62100	95700	118100	138900	144700	—	—	—	—
1,000	76900	118100	145900	171300	178900	—	—	—	—
1,200	110800	170100	209800	—	—	—	—	—	—

 

When calculating the mass, the density of polyethylene is 950 kg / m³.

Characteristics of gas pipes

GOST for polyethylene products intended for gas, their required technical parameters are established. Some of the indicators are common for both grades of material (80 and 100). So, the installed density should be more than 930 kg / m³, the spread of MFIs is ± 20%, the mass fraction of soot (carbon black) is 2.0-2.5%, and the volatiles are not more than 350 mg / kg.

Indicators that are different for different grades of polyethylene are given in the table (symbol: BRT - rapid crack propagation).

Table 13

Index	The value for the brand of polyethylene, * 10		unit of measurement
	100	80
PTR at 190º / 5 kgf	0,01-0,05	0,03-0,12	g / 10 minutes
Resistance to MRI at a temperature of 80 degrees for products with a nominal diameter of 160 or 110 mm and SDR 11	50 (at an initial voltage of 4600 kPa)	50 (at an initial voltage of 4 thousand kPa)	no less than

 

Pipes for gas from different grades differ in the calculated safety factor, which is given in the table.

Table 14

Maximum working pressure, kPa		Safety factor
		300	400	600	800	1000	1200
For PE 80	SDR 26	2,1	—	—	—	—	—
	SDR 21	2,7	2,0	—	—	—	—
	SDR 17.6	3,2	2,4	—	—	—	—
	SDR 17	3,3	2,5	—	—	—	—
	SDR 13.6	4,2	3,2	2,1	—	—	—
	SDR 11	5,3	4,0	2,7	2,0	—	—
	SDR 9	6,7	5,0	3,3	2,5	2,0	—
For PE 100	SDR 26	2,7	2,0	—	—	—	—
	SDR 21	3,3	2,5	—	—	—	—
	SDR 17.6	4,0	3,0	2,0	—	—	—
	SDR 17	4,2	3,1	2,1	—	—	—
	SDR 13.6	5,3	4,0	2,6	—	—	—
	SDR 11	6,7	5,0	3,3	2,5	2,0	—
	SDR 9	8,3	6,2	4,2	3,1	2,5	2,1

 

HDPE pipe for cable

GOST 18599 defines the characteristics and technical pipes that can be used for laying and protecting cables.

Note! In the manufacture of such a product, the use of secondary raw materials is allowed (in agreement with the consumer), which reduces the base cost by about 50%.

Pipes for cables made of polyethylene are beneficial not only financially, but also in practical terms. Such communications do not withstand internal pressure, which leads to the limitation of their use:

• for pressureless sewerage;
• like a case for a power cable.

Technical pipes are usually supplied in bays of one hundred or two hundred meters, as well as segments of 12 meters. Different wall thickness determines the assignment of the product to one of the options for stiffness (see table).

Table 15

SDR	26	21	17,6	13,6	11	9
A type	"SL"	"OS"	"WITH"	"ST"	"T"	"FROM"

 

Assortment of technical pipes

Technical pipes have the characteristics presented in the table.

Table 16

Diameter, * 10-1 mm	Type "SL"		Type "OS"		Type "C"		Type "ST"		Type "T"
	Weight g	Wall, * 10-2 mm	Weight g	Wall, * 10-2 mm	Weight g	Wall, * 10-2 mm	Weight g	Wall, * 10-2 mm	Weight g	Wall, * 10-2 mm
160	—	—	—	—	—	—	—	—	92	200
200	—	—	—	—	—	—	—	—	116	200
250	—	—	—	—	—	—	148	200	169	230
320	—	—	—	—	197	200	229	240	277	300
400	—	—	—	—	281	230	353	300	427	370
500	—	—	—	—	436	290	545	370	663	460
630	—	—	573	300	682	360	869	470	1050	580
750	—	—	821	360	970	430	1230	560	1460	680
900	969	350	1180	430	1400	520	1760	670	2120	820
1100	1420	420	1770	530	2070	630	2610	810	3140	1000
1250	1830	480	2260	600	2660	710	3370	920	4080	1140
1400	2310	540	2830	670	3350	800	4220	1030	5080	1270
1600	3030	620	3710	770	4350	910	5500	1180	6670	1460
1800	3780	690	4660	860	5470	1020	6980	1330	8430	1640
2000	4680	770	5770	960	6780	1140	8560	1470	10400	1820
2250	5880	860	7290	1080	8550	1280	10900	1660	13200	2050
2500	7290	960	8920	1190	1060	1420	13400	1840	16200	2270

 

Advantages of HDPE pipes over steel

Polymer pipes are very common now. The breadth of their use is determined by a number of positive characteristics.

PE products are much cheaper than steel pipes and have a guaranteed operational life of at least fifty years. Since PND pipes (GOST 18599, 22689, 32415 and 50838) do not require the use of cathodic protection, there is no need for their further maintenance.

Such products are not afraid of corrosion, exposure to chemicals. Thanks to their low weight installation work. In addition, the installation is cheaper due to the butt welding of PE pipes. Water frozen inside the pipeline does not destroy it, while maintaining complete tightness and integrity.

HDPE pressure pipes protect well against microorganisms and bacteria. The smooth inner surface provides excellent throughput. When using such pipes, the purity of the transported liquid is guaranteed, which makes it possible to arrange drinking water pipelines based on polyethylene products.

Features of marking HDPE pipes

Information about the characteristics of products, expressed in alphanumeric form, is available on the outer surface of the pipes. The ability to read such markings greatly simplifies the process of choosing the right communication and allows you to avoid critical errors during the assembly of the pipeline.

Labeling of polyethylene products includes the name of the manufacturer, as well as the designation of the standard by which such products are made, for example, GOST 18599.

Note! The name of the pipe material has an international format: PE 100 (or 63, or 80).

After the polymer grade, a group of numbers is indicated that corresponds to the outer diameter. This value is given in millimeters and corresponds to the assortment. In addition to the external dimensions, the marking also includes the internal - wall thickness. It is also expressed in millimeters.

An important characteristic that you should definitely pay attention to when choosing a PND pipe is the nominal pressure. Sometimes manufacturers also indicate the maximum value of this parameter, expressed in MPa.

The final marking position is the batch number and production date.

PE heat resistant

GOST 32415 identifies a special type of polyethylene having increased heat resistance. The assortment is given in the table.

Table 17

Series	2,5	3,2	4	5	6,3	8
SRO	6	7,4	9	11	13,6	17
Diameter, * 102 mm	Product wall * 10-2mm
0,10	170	140	130	130	130	130
0,12	200	180	140	130	130	130
0,16	270	220	180	150	130	130
0,20	340	280	230	190	150	130
0,25	420	350	280	230	190	150
0,32	540	440	360	290	240	190
0,40	670	550	450	370	300	240
0,50	830	690	560	460	370	300
0,63	1050	860	710	580	470	380
0,75	1250	1030	840	680	560	450
0,90	1500	1230	1010	820	670	540
1,10	1830	1510	1230	1000	810	660
1,25	2080	1710	1400	1140	920	740
1,40	2330	1920	1570	1270	1030	830
1,60	2660	2190	1790	1460	1180	950
1,80	2990	2460	2000	1640	1330	1070
2,00	3320	2740	2240	1820	1470	1190
2,25	3740	3080	2520	2050	1660	1340
2,50	4150	3420	2790	2270	1840	1480
2,80	4650	3830	3130	2540	2060	1660
3,15	5230	4310	3520	2860	2320	1870
3,55	5900	4850	3970	3220	2610	2110
4,00	6650	5470	4470	3630	2940	2370
4,50	—	6150	5030	4090	3310	2670
5,00	—	6830	5580	4540	3680	2970
5,60	—	—	6250	5080	4120	3320
6,30	—	—	—	5720	4630	3740
7,10	—	—	—	6450	—	—

 

Such pipes can be produced in straight sections, coils, bays. The deviation of products with a length of up to 12 meters should be 10 mm up (or down). Maximum dimensional deviations and ovality are given in the table.

Table 18

Diameter, * 100 mm	Deviation upwards, mm	Permissible ovality, no more than * 10-1 mm
0,10	0,3	11
0,12	0,3	11
0,16	0,3	12
0,20	0,3	12
0,25	0,3	12
0,32	0,3	13
0,40	0,4	14
0,50	0,5	14
0,63	0,6	16
0,75	0,7	16
0,90	0,9	18
1,10	1,0	22
1,25	1,2	25
1,40	1,3	28
1,60	1,5	32
1,80	1,7	36
2,00	1,8	40
2,25	2,1	45
2,50	2,3	50
2,80	2,5	98
3,15	2,8	111
3,55	3,2	125
4,00	3,6	140
4,50	3,8	158
5,00	4,0	175
5,60	4,3	196
6,30	4,6	221
7,10	4,9	—

 

Crosslinked Polyethylene Properties

Regulatory documents (for example, GOST 32415) govern the technical characteristics and conditions of use of another type of polymer material - cross-linked polyethylene.

Conventional HDPE polyethylene is obtained in the presence of catalysts under low pressure. Its structure includes molecules with a significant number of branches, most of which are in space in a free state.

Note! After stitching, side bonds are additionally formed, forming an intermolecular network, which is distinguished by its special strength.

Various crosslinking technologies lead to an increase or decrease in the number of such bonds, which affects the characteristics of the product. For example, PEX-a polymer is obtained by a more expensive method, but it has the highest crack resistance, impact resistance and the highest melting point.

Crosslinked Polyethylene Parameters

Standards define all the technical parameters of the material. So, its density is 940 kg / m³, the melting point is +200 degrees, the thermal conductivity is 0.38 W / m * K. Crosslinked polyethylene has tensile strengths of 350 to 800% and a very high level of flexibility. Pipes made of such a polymer are characterized by increased throughput, which is 20-30 percent higher than the same indicator for other communications. Tubular joints are also characterized by increased strength.

The negative properties of the material include instability to ultraviolet radiation, which, after prolonged exposure, leads to its fragility and slow destruction, as well as the destructive effect of oxygen (O₂) upon penetration into the molecular structure of a substance.

PND pipe (GOST 32415, 22689, 18599 and 50838) is a high-quality product with a number of positive qualities. The technical characteristics established by the standards allow them to be applied in many fields and for various pipelines.