PVC pressure pipe, SDR 21 series (solvent-weld joints)

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Rigid PVC pipe for pressurized water conduction with solvent-weld joints, SDR 21 series per NTC 382:2018 (based on ASTM D2241). Working pressure 200 psi (13.8 bar) with water at 23 °C, constant from 3/4″ to 6″. Cell class 12454 compound (ASTM D1784), material designation PVC 1120. 6 m lengths, 10 diameters from 1/2″ to 6″.

SKU VT-156410 · SDR 21 PVC pressure pipe, plain end for solvent welding · 6 m lengths · price from $27,000 COP + VAT per length (Jul 2026, confirmed on quotation)

1. Technical specifications

Dimensions and working pressure by diameter — SDR 21 series

¹ Reference ID = OD − 2 × minimum wall (theoretical maximum; the actual bore depends on the manufacturer's average wall). Dimensions per ASTM D2241, Tables 1 and 2, adopted by NTC 382:2018. Wall tolerance is plus-only: the minimum wall is guaranteed at any cross-section of the pipe.

² In 1/2″ the NTC 382 / ASTM D2241 tables do not list SDR 21: the resulting wall (1.02 mm) would fall below the minimum manufacturing wall the standard sets (1.52 mm · 0.060 in). The size is supplied with the minimum wall the standard assigns to 1/2″ (1.57 mm, SDR 13.5), whose working pressure is 315 psi — higher than the rest of the series. The exact series of the lot is confirmed on quotation.

³ In 3/4″ the normative minimum-wall floor applies (1.52 mm > 26.67/21 = 1.27 mm), giving an effective SDR ≈ 17.5; the working pressure assigned to the series is still 200 psi.

General specifications

Product	Rigid PVC pipe for pressurized liquid conduction, SDR 21 series, plain end for solvent-cemented joints
Material	PVC compound, cell class 12454 per ASTM D1784-25; material designation PVC 1120 (Type I, Grade 1, HDS 2,000 psi — see section 3)
Product standard	NTC 382:2018 — Poly(vinyl chloride) (PVC) pipe classified by pressure (SDR series); based on ASTM D2241 (current edition D2241-25a)
Working pressure	200 psi · 13.8 bar · 1.38 MPa with water at 23 °C, constant from 3/4″ to 6″ (calculation basis in section 2). Does not apply to threaded pipe (ASTM D2241, Table X1.1, note A).
Standard tests (SDR 21)	Sustained pressure: 420 psi for 1,000 h without failure (ASTM D1598). Minimum burst pressure: 630 psi (ASTM D1599). Flattening to 40 % of OD without cracking. Extrusion quality by acetone immersion (ASTM D2152). — D2241, Tables 3 and 4 / NTC 382.
Joining system	Solvent welding (solvent cement per NTC 576:2021) between the plain pipe end and the fitting socket; pressure fittings certified under NTC 1339 (see section 5)
Commercial length	6 m per length
Service temperature	Water up to 60 °C applying the factors in section 2 (at 43 °C the allowable pressure drops to 50 %; at 60 °C to 22 %). Not suitable for domestic hot water: that application belongs to CPVC or metallic pipe.
Fluids	Pressurized liquids chemically compatible with PVC (scope of D2241/NTC 382). Use and testing with compressed air or other gases is prohibited (D2241, cl. 1.2).
Dimensional tolerances	Average OD: ±0.10 mm (1/2″) to ±0.28 mm (6″); wall: plus-only tolerance over the minimum wall (D2241, Tables 1 and 2)
Normative pipe marking	Nominal size · material designation (PVC 1120) · SDR or pressure rating (e.g. “200 PSI”) · standard (NTC 382 / D2241) · manufacturer and lot code · seal of the laboratory certifying potable-water suitability, at intervals ≤ 1.5 m

2. Calculation basis (the SDR series formula)

SDR (Standard Dimension Ratio, RDE in Spanish) is the ratio of outside diameter to minimum wall thickness: SDR = D/t. Because diameter and wall grow in the same proportion, the working pressure of a given SDR is constant and independent of diameter — that is why every pipe in this series, from 3/4″ to 6″, is rated 200 psi. The relation between SDR and pressure is the “ISO equation” that NTC 382 and ASTM D2241 use to classify the pipe (D2241, cl. 3.2.3). All values used are stated below — nothing is assumed silently:

HDB — hydrostatic design basis	HDB = 27.58 MPa (4,000 psi) for the PVC 1120 compound (cell class 12454) with water at 23 °C: long-term hoop stress obtained by regression of sustained-pressure tests and extrapolated to 100,000 h per ASTM D2837-22. Value listed by the Plastics Pipe Institute in PPI TR-4 (2024 ed.).
DF — design factor	DF = 0.5: service factor recommended by PPI and adopted by D2241/NTC 382 for water at 23 °C. Equivalent to a 2:1 long-term safety factor over the extrapolated strength of the material.
HDS — hydrostatic design stress	HDS = HDB × DF = 4,000 × 0.5 = 2,000 psi (13.79 MPa), per ASTM D2241, Appendix X1 (PPI-recommended values for water at 23 °C).
SDR — dimension ratio	SDR = average OD / minimum wall thickness. The calculation uses the minimum wall directly because the standard's wall tolerance is plus-only (the actual wall never falls below the minimum) — unlike steel, no manufacturing tolerance is deducted here.

Working pressure by SDR — water at 23 °C, PVC 1120 compound

SDR	Calculated P = 2·HDS/(SDR−1)	Pressure assigned by the standard	bar
13.5	320 psi	315 psi	21.7
17	250 psi	250 psi	17.2
21	200 psi	200 psi	13.8
26	160 psi	160 psi	11.0
32.5	127 psi	125 psi	8.6
41	100 psi	100 psi	6.9
64	63.5 psi	63 psi	4.3

Assigned pressures per ASTM D2241, Table X1.1 (the standard rounds down to preferred numbers when the calculation is not a whole value). These pressures do not apply to threaded pipe. NTC 382:2018 classifies the same SDR series for the Colombian market; local manufacturers also offer SDR 9 (500 psi) and SDR 11 (400 psi) — same formulas.

Temperature derating — factors over the 23 °C working pressure

PVC strength drops with temperature. Multiply the working pressure by the factor for the sustained service temperature (source: Handbook of PVC Pipe — Design and Construction, Uni-Bell PVC Pipe Association; table republished by major manufacturers):

Service temperature		Factor	Resulting SDR 21
°C	°F		psi	bar
23 °C	73 °F	1.00	200	13.8
27 °C	80 °F	0.88	176	12.1
32 °C	90 °F	0.75	150	10.3
38 °C	100 °F	0.62	124	8.5
43 °C	110 °F	0.50	100	6.9
49 °C	120 °F	0.40	80	5.5
54 °C	130 °F	0.30	60	4.1
60 °C	140 °F	0.22	44	3.0

At 43 °C the pipe keeps only 50 % of its working pressure, and at 60 °C, 22 %. 60 °C (140 °F) is the maximum recommended operating temperature for PVC pressure pipe. Below 23 °C the published values are conservative.

3. Cell class 12454 and the PVC 1120 designation

The pipe compound is specified by its cell classification per ASTM D1784-25: five digits that set verifiable minimum requirements for the material. Cell class 12454 is the one required for nearly all PVC pressure pipe:

Digit	Property	Minimum required value (cell class 12454)
1	Base resin	1 = poly(vinyl chloride) homopolymer
2	Izod impact resistance	2 = ≥ 34.7 J/m (0.65 ft·lbf/in)
4	Tensile strength	4 = ≥ 48.3 MPa (7,000 psi)
5	Tensile modulus of elasticity	5 = ≥ 2,758 MPa (400,000 psi)
4	Deflection temperature under load	4 = ≥ 70 °C (158 °F)

The 2,758 MPa modulus — about 70 times lower than steel's — is the physical reason behind two behaviors this data sheet quantifies: water hammer is much lower than in metallic pipe (section 4), and the pipe's stiffness requires continuous bedding during installation.

What “PVC 1120” means

The material designation the standard requires to be marked on the pipe reads as follows (D2241, cl. 3.2.5 and Appendix X1): PVC = plastic type · 1 = ASTM Type I (cell class 12454) · 1 = Grade 1 · 20 = hydrostatic design stress in hundreds of psi (20 × 100 = 2,000 psi with water at 23 °C). In other words: the material's own name declares the HDS that feeds the formula in section 2. A pipe marked PVC 1120 · SDR 21 · NTC 382 carries its full pressure classification in plain sight.

4. Water hammer (pressure surge)

A sudden change in water velocity (valve closure, pump stop) creates a surge wave ΔP = ρ · a · ΔV, where “a” is the wave celerity in the pipe. Celerity — and with it the surge — grows with pipe stiffness: since PVC's modulus (≥ 2,758 MPa, section 3) is a fraction of any metal's, the same transient produces a surge several times smaller in PVC than in metallic pipe. In a 6″ main with an instantaneous 0.6 m/s change, Class 350 ductile iron generates 109 psi (751 kPa) of surge while SDR 26 PVC generates 28.8 psi (202 kPa) — 3.8 times less (design table, Handbook of PVC Pipe, Uni-Bell).

Surge by SDR — per 0.30 m/s (1 ft/s) of instantaneous velocity change

SDR	Surge ΔP
13.5	20.2 psi · 139 kPa
17	17.9 psi · 123 kPa
21	16.0 psi · 110 kPa
26	14.4 psi · 99 kPa
32.5	12.8 psi · 88 kPa
41	11.4 psi · 79 kPa

Design table for cell-class 12454 PVC pipe (Handbook of PVC Pipe — Design and Construction, Uni-Bell). More wall (lower SDR) means a stiffer pipe and a higher surge. From the SDR 21 row the celerity follows: a = ΔP/(ρ·ΔV) = 110,300 Pa / (998 kg/m³ × 0.3048 m/s) ≈ 360 m/s — versus the several-times-higher celerity of rigid metallic pipe.

Surge-control rules: slow valve closure (several seconds, proportional to line length), pump start against a partially closed valve, filling velocity ≤ 0.3 m/s until all air is purged, and double-acting air valves at high points — trapped air amplifies transients.

5. Solvent-weld (solvent cement) joints

This series joins by solvent welding: the solvent cement dissolves the surfaces of the plain pipe end and the fitting socket, which fuse as the solvent evaporates, forming a continuous joint. The cement must comply with NTC 576:2021 (sixth edition; based on ASTM D2564), which requires tests for dissolving capacity, shear strength of the bonded zone and hydrostatic burst strength of the joint. Socket fittings belong to the pressure line certified under NTC 1339.

Making the joint

1. Dry fit	Before applying cement, test pipe and fitting: there must be interference (the pipe enters snug, not loose). Cut the pipe square and deburr.
2. Cleaning	Clean the pipe end and the socket with primer/cleaner even if they look clean; never join wet surfaces or work under rain.
3. Application	Apply a generous coat of cement on the pipe and a light coat in the socket, using a natural-bristle brush about half the pipe diameter wide. Insert fully at once: the whole operation must take less than 1 minute.
4. Verification	A properly made joint shows a continuous cement bead around the perimeter — do not remove it. Avoid excess: active cement inside the pipe weakens the wall.
5. Curing	Let the joint set ≈ 1 h before moving the line and ≈ 24 h before hydrostatic testing. Exact times depend on the cement, diameter, temperature and humidity: the cement manufacturer's cure table governs.

Do not thread SDR-series pipe: the pressures in this data sheet do not apply to threaded pipe (D2241, Table X1.1, note A) — threading removes wall from an already-minimum thickness. For threaded transitions use pressure adapters from the fittings line; for transitions to metallic pipe, dedicated adapters or couplings. Line testing is always done with water: the standard prohibits testing with compressed air or other gases (D2241, cl. 1.2).

6. Sunlight (UV) exposure and storage

UV radiation degrades only the exposed surface of PVC: it causes discoloration and a gradual loss of impact strength. In the aging study by the Uni-Bell PVC Pipe Association (report UNI-TR-5, “The Effects of Ultraviolet Aging on PVC Pipe”), the lowest impact strength after 2 years of continuous outdoor exposure was ≈ 75 % of the original ASTM-required value; tensile strength and modulus of elasticity were virtually unaffected, so pressure capacity does not change. Exposed pipe becomes more brittle against impact, not weaker against pressure.

• Outdoor installation: degradation stops with any opaque barrier — UV radiation does not penetrate thin coatings. The recommended protection is light-colored water-based latex paint or an opaque wrap. Do not apply solvents or paints that attack PVC.
• Storage: under cover, with continuous support along the full length, away from heat sources that could deform the thermoplastic and from sharp objects.
• Thermal expansion: in exposed runs with temperature swings above 15 °C, allow for expansion with direction changes or expansion offsets; buried runs at stable temperature do not require it.

7. Application notes

8. Technical notice and limitation of liability