Rates Of Thermal Expansion For Common Pipe Materials

In modern HVAC, energy, and process industries, pipe material selection is not just about cost or standard practices—it’s about anticipating expansion and contraction risks driven by a dynamic climate and extreme operational temperatures. Understanding the rates of thermal expansion for common pipe materials is foundational for performance, reliability, and lifecycle cost optimization.

High-Level View

Thermal expansion (or contraction) in pipes occurs when temperature changes—be it from media flow, ambient conditions, solar gain, or wind chill. Left unaccounted for, expansion leads to misalignment, mechanical stress, and even system failure.

Formula to Calculate Linear Expansion:

$$X = L \times (T_2 – T_1) \times C_{\text{exp}}$$

• X: Change in length (meters)
• L: Original length (meters)
• T1/T2: Initial and final temperature (°C)
• Cexp: Coefficient of thermal expansion (per °C)

Key Patterns and Quantified Metrics

Different materials expand at different rates, and plastics outpace metals by an order of magnitude—critical for mixed-material system designs. Below are coefficients (as per reliable industry tables):

Material	Coefficient (x10⁻⁶ /°C)	Example: ΔL per meter from 0–100°C (mm)
Copper	16.4	1.64
Carbon Steel	12.2	1.22
Stainless Steel (Austenitic)	16.3	1.63
Stainless Steel (Ferritic)	10.9	1.09
Cast Iron	11.0	1.10
ABS (Plastic)	100	10.0
PVCu	80	8.0
PE (Polyethylene)	200	20.0
PP (Polypropylene)	150	15.0

Key Insight:

• Plastics (ABS, PVCu, PE, PP) expand anywhere from 5× to 15× more than most metals for the same temperature range1.
• For every 10°C increase, a polyethylene pipe expands 2 mm per meter—while carbon steel expands only 0.12 mm.

Actionable Table: Expansion Rates (mm per Meter)

Temperature Change °C	Copper	Carbon Steel	Stainless Steel	Cast Iron	ABS	PVCU	PVCC	PE	PP
10	0.16	0.12	0.16	0.11	1.00	0.80	0.70	2.00	1.50
20	0.33	0.24	0.33	0.22	2.00	1.60	1.40	4.00	3.00
30	0.49	0.37	0.49	0.33	3.00	2.40	2.10	6.00	4.50
40	0.66	0.49	0.65	0.44	4.00	3.20	2.80	8.00	6.00
50	0.82	0.61	0.82	0.55	5.00	4.00	3.50	10.00	7.50
60	0.98	0.73	0.98	0.66	6.00	4.80	4.20	12.00	9.00
70	1.15	0.85	1.14	0.77			4.90		10.50
80	1.31	0.98	1.30	0.88			5.60		12.00
90	1.48	1.10	1.47	0.99
100	1.64	1.22	1.63	1.10
110	1.80	1.34	1.79	1.21
120	1.97	1.46	1.96	1.32
130	2.13	1.59	2.12	1.43
140	2.30	1.71	2.28	1.54
150	2.46	1.83	2.45	1.65
160	2.62	1.95	2.61
170	2.79	2.07	2.77
180	2.95	2.20	2.93
190	3.12	2.32	3.10
200	3.28	2.44	3.26
210		2.56	3.42
220		2.68	3.59
230		2.81	3.75
240		2.93	3.91
250		3.05	4.08
260		3.17	4.24
270		3.29	4.40
280		3.42	4.56
290		3.54	4.73
300		3.66	4.89

Strategic Takeaways & Proactive Recommendations

• Plastic piping (e.g., PE, PP) requires deliberate expansion joints or directional changes to avoid failure under fluctuating temperatures—especially outdoors or near machinery.
• Metal piping is less susceptible but can still accumulate significant stress in long runs or systems with temperature swings exceeding 100°C.
• Design with Margin: Use the expansion formula to calculate total expected growth/shrinkage over the pipe’s full operative temperature range, and specify compensators, guides, or anchors accordingly.
• Mixed Systems: Never assume compatibility—always calculate the differential movement of joined materials.

Identify, Quantify, Optimize
For new installations or retrofits:

• Audit all relevant pipe runs for temperature extremes.
• Calculate worst-case expansions per material.
• Specify mitigation: e.g., expansion loops, flexible connectors.

Pipe Thermal Expansion Calculator