1. DEVELOPMENT OF AN ITALIAN FIRE PREVENTION
TECHNICAL RULE FOR HYDROGEN PIPELINES
N. Mattei, M. Carcassi., N. Ciannelli, F. Pilo
Università di Pisa
Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione (DIMNP),
University of Pisa
ICHS San Francisco, USA - September

2. SUMMARY Italian regulation about hydrogen and methane
Italian development of regulation
Italian Working Group on Hydrogen
Experimental facility and tests
Data acquired and data elaboration
Procedure followed to define safety distance
Conclusions
ICHS San Francisco, USA - September

3. REGULATION IN FORCE IN ITALY
Right now no law or technical rule is available to install a pipeline for hydrogen
Rules referring to natural gas and and gas with r ≤ 0.8 [kg/m3] must be followed:
“D.M 16 aprile 2008” (distribution)
“D.M. 17 aprile 2008” (transport)
Moreover European laws already cover many aspects involved in design, building and safety issues, e.g. DIRECTIVE 97/23/EC (PED).
ICHS San Francisco, USA - September

4. Italian Working Group on Fire Prevention
Italian Methodology
Ministry of Interior
REGULATION
Experimenthal activity
CCTS
FIRE PREVENTION
TECHNICAL RULE FOR HYDROGEN PIPELINES
Hydrogen
Italian Working Group on Fire Prevention
“D.M 16 aprile 2008” (distribution)
Methane
“D.M. 17 aprile 2008” (transport)
ICHS San Francisco, USA - September

5. METHANE SAFETY DISTANCES Gauge Pressure inside pipe [MPa]
1° Type
2.4 < P ≤ 6
2° Type
1.2 < P ≤ 2.4
3° Type
0.5 < P ≤ 1.2
Categories A B D
Pipe Diameter [mm]
Safety Distance [m]
≤ 100 30 10
2.0 20 7 5
1.5
125
2.5
150
3.0
175
3.5
200
4.0
225
4.5
250
5.0
300
6.0
350
7.0
400
8.0
450
9.0
6.5
> 500
10.0
ICHS San Francisco, USA - September

6. to validate the calculation models
EXPERIMETAL TESTS
The Group has decided to support its work with an experimental activity, by means of a pilot plant named H.P.B.T. (Hydrogen Pipe Break Test) at University of Pisa.
The plant has been used to:
simulate hydrogen release
its ignition and development of combustion.
Data have been acquired about:
the diffusivity of the gas
the dimension of release jet
the dimension of jet-fire
as function of internal pressure and release hole diameter.
to validate the calculation models
ICHS San Francisco, USA - September

7. HPBT LAYOUT
ICHS San Francisco, USA - September

8. PARAMETERS OF EXPERIMENTAL TESTS
According to the draft, pipelines are categorized as function of internal pressure and diameter.
The incidental scenario is defined by:
Internal pressure (test pressure: up to 10 bar)
release hole diameter/area (2.5 / 5; 5 / 20 and 11 / 95 mm / mm2)
Hole diameter and internal pressure have been chosen in order to have a “steady” jet so that it was possible to measure it
ICHS San Francisco, USA - September

9. DISPLACEMENT OF 9 SAMPLE POINTS
HPBT-JR-8
HPBT-JR-8
HPBT-JR-19
x [mm]
y [mm]
z [mm] X4
290
-10 X5
500 20 X6
980 X7
2000 X8
2490 X9
480 70
X10
-50
X11
100
X12
-100
x [mm]
y [mm]
z [mm] X4
620 X5
930 X6
2000
320 X7 X8
3060 50
430 X9
-320
X10
1230
X11
240
X12
ICHS San Francisco, USA - September

10. AVAILABLE FOR EACH TEST H2 concentration vs. time
SUMMARY OF DATA
AVAILABLE FOR EACH TEST
angle between wind direction and jet axis
wind velocity
spatial coordinates of sample points
H2 concentration vs. time
ICHS San Francisco, USA - September

11. EXAMPLE OF DATA ACQUIRED
(Ø 2,5mm and P = 10bar)
Start of release
Temperature [°C]
inside tanks
Oxygen
Concentration
[%vol]
Temperature [°C] next
to release hole
Pressure [barg]
inside tanks
ICHS San Francisco, USA - September

12. DATA ACQUIRED wind veolcity
ICHS San Francisco, USA - September

13. JET-FIRE DIMENSION Ø 11 mm - P 10 bar Lateral view Front view 4 m
ICHS San Francisco, USA - September

14. JET FIRE DATA ACQUIRED Internal Pressure [bar] Ø = 2.5 mm Ø = 11 mm
Flame length [m]
ICHS San Francisco, USA - September

15. CODE SIMULATION - EFFECTS 7.6
ICHS San Francisco, USA - September

16. CODE SIMULATION - FLACS v9.0 (CFD)
ICHS San Francisco, USA - September

17. COMPARISON BETWEEN EXPERIMETAL DATA AND COMPUTER SIMULATION
CENTRAL AXYS [m]
ICHS San Francisco, USA - September

18. RADIATIVE ENERGY PRODUCED BY A JET-FIRE DISTANCE FROM RELEASE HOLE
vs.
DISTANCE FROM RELEASE HOLE
[m]
kW/m2
5.4
12.5
ICHS San Francisco, USA - September

19. HEAT RADIATION (EFFECT)
Hydrogen and methane radiative power
due to equal hole and pressure
hydrogen
[kW/m2]
methane
5,4
6,8
[m]
ICHS San Francisco, USA - September

20. COMPARISON BETWEEN H2 AND CH4 FLOW
critic flow
mass flow
energy flow
same T and P
same T and P
same area
ICHS San Francisco, USA - September

21. PROCEDURE FOLLOWED TO DEFINE SAFETY DISTANCE
Pipes are categorized as a function of pressure and pipe diameter.
A release hole diameter is associated to pipe diameter (Ø hole = 2.5% of pipe diameter).
The resulting jet fire allows to evaluate the distance beyond which radiative power is lower than a defined value (3 kW/m2 according to Italian laws). (1)
(1) D.M. 29 Maggio 2001: following the law, a person can be exposed to such a radiation undergoing to no more that reversible injuries
ICHS San Francisco, USA - September

22. PROPOSED SAFETY DISTANCES Gauge Pressure allowed inside pipe [MPa]
1° Type
2.4 < P ≤ 6
2° Type
1.2 < P ≤ 2.4
3° Type
0.5 < P ≤ 1.2
Categories E
Pipe Diameter [mm]
Safety Distance [m]
≤ 100
3.5
3.0
2.5
125
4.0
150
5.0
4.5
175
5.5
200
6.0
225
7.0
6.5
250
7.5
300
9.0
8.5
350
10.5
9.5
400
12.0
11.0
8.0
450
13.5
> 500
15.0
10.0
ICHS San Francisco, USA - September

23. Nicola Mattei (UNIPI-ITALY) n.mattei@ing.unipi.it
THANK YOU.
Contact Author:
Nicola Mattei (UNIPI-ITALY)
Presented by:
Marco Carcassi (UNIPI-ITALY)
ICHS San Francisco, USA - September