E-glass needle mat — properties, λ(T) and computed performance

Service limit ≈550 °C · density 120–160 kg/m³ · needled E-glass per supplier datasheets (no binder — no smoke on first heat). Supplied as: needled fibreglass mat — the standard CORE of removable insulation covers.

Honest assessment

Strengths, limits, verdict

Strengths: binder-free (no first-fire smoke), flexible, vibration-tolerant, sews cleanly into covers; handles 550 °C.

Limits: as a loose mat needs containment (it is a cover core, not a clad-and-jacket material).

Verdict: If the job is a removable cover up to ~550 °C, this is what is inside it.

Thermal conductivity (typical published values)

Mean temperature	λ W/m·K
100 °C	0.045
200 °C	0.058
300 °C	0.075
400 °C	0.095

λ at mean temperature — rises with T because pore radiation grows with T³.

Computed performance · ASTM C680 simplified

E-glass needle mat on real pipe sizes

At 100 °C (λ=0.045 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	152	30	28 °C	€60	0.22
DN50	50 mm	152	22	24 °C	€63	0.23
DN50	100 mm	152	15	22 °C	€67	0.24
DN100	30 mm	287	48	29 °C	€117	0.43
DN100	50 mm	287	34	25 °C	€124	0.45
DN100	100 mm	287	22	22 °C	€130	0.47
DN200	30 mm	551	82	29 °C	€228	0.84
DN200	50 mm	551	56	26 °C	€241	0.88
DN200	100 mm	551	34	23 °C	€252	0.92

At 250 °C (λ=0.050 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	436	93	45 °C	€167	0.61
DN50	50 mm	436	69	34 °C	€179	0.65
DN50	100 mm	436	48	26 °C	€189	0.69
DN100	30 mm	826	150	47 °C	€330	1.21
DN100	50 mm	826	106	36 °C	€351	1.29
DN100	100 mm	826	69	27 °C	€369	1.35
DN200	30 mm	1,583	258	49 °C	€646	2.37
DN200	50 mm	1,583	176	38 °C	€686	2.51
DN200	100 mm	1,583	107	28 °C	€720	2.64

At 400 °C (λ=0.060 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	720	180	68 °C	€263	0.96
DN50	50 mm	720	135	47 °C	€285	1.04
DN50	100 mm	720	94	32 °C	€305	1.12
DN100	30 mm	1,365	291	73 °C	€524	1.92
DN100	50 mm	1,365	208	51 °C	€564	2.06
DN100	100 mm	1,365	136	34 °C	€599	2.19
DN200	30 mm	2,616	500	77 °C	€1,032	3.78
DN200	50 mm	2,616	345	54 °C	€1,108	4.05
DN200	100 mm	2,616	211	36 °C	€1,173	4.29

Assumptions: 20 °C ambient, still air (h=10 W/m²·K), €0.05/kWh fuel, 8000 h/yr, 82% boiler efficiency, 0.183 kg CO2e/kWh. Your numbers: free calculator.

Against the field

Same duty, all materials — DN100 at 250 °C

Material	λ W/m·K	Loss W/m	Surface	Saving €/m·yr	t CO2/m·yr
Stone wool (mineral wool)	0.052	112	37 °C	€348	1.3
Glass wool	0.050	106	36 °C	€351	1.3
Ceramic fibre (RCF / AES blanket)	0.060	127	39 °C	€341	1.2
Aerogel blanket	0.027	61	29 °C	€373	1.4
Calcium silicate	0.067	139	41 °C	€335	1.2
Expanded perlite	0.070	145	42 °C	€332	1.2
Cellular glass	0.058	122	38 °C	€343	1.3
Microporous (fumed-silica) panels	0.023	50	27 °C	€378	1.4
E-glass needle mat	0.050	106	36 °C	€351	1.3
Silica needle mat / fabric	0.055	117	37 °C	€346	1.3

DN100 pipe at 250 °C, 50 mm insulation, per metre of pipe; bare loss 826 W/m. λ at mean temperature; € and CO2 per metre·year at €0.05/kWh, 8000 h, 82% efficiency. Method: ASTM C680 simplified (h=10).

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FAQ

Questions on this topic

What is the thermal conductivity of e-glass needle mat?

Typical published values: 0.045 W/m·K at 100 °C, 0.058 W/m·K at 200 °C, 0.075 W/m·K at 300 °C, 0.095 W/m·K at 400 °C (mean temperature). λ rises with temperature — design with the mean-temperature value, not the ambient one.

What is the maximum temperature for e-glass needle mat?

≈550 °C continuous service for typical grades (needled E-glass per supplier datasheets (no binder — no smoke on first heat)). Product-specific limits vary — check the datasheet of the exact grade.

Where is e-glass needle mat the right choice?

If the job is a removable cover up to ~550 °C, this is what is inside it.