Hazardous Areas Current trends in industry

Transcription

1 Hazardous Areas Current trends in industry Carolyn Yates Technical Director, Energy and Resources Aurecon Northern Territory

2 Hazardous Areas Current trends in industry Overview A few hazardous area basics Classification Explosion protection techniques and equipment Current trends in area classification Design and installation Inspection and maintenance Common myths Some of the interesting stuff 2

3 Introduction The disclaimer.. Before we start, this presentation is based on Australian requirements and jurisdictions. When working on projects in other areas of the world, it is important to find out what the requirements are in the location and follow them. This presentation is designed to give a basic introduction to hazardous areas and to provide some of my own experiences as hazardous area designer, inspector and auditor. It is not a competency course. 3

4 What is a hazardous area? Definition: Hazardous area Hazardous area definitions are found in several Australian Standards. This definition for a hazardous area comes from AS/NZS 3000 Clause Area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment [AS/NZS ]. 4

5 What is a hazardous area? What does it really mean? An area that contains, or is reasonably expected to contain flammable gases or vapours or combustible dusts, fibres or flyings. Generally if you have flammable gases or liquids, or combustible dusts, you will most likely have a hazardous area. 5

6 Around Darwin.. Darwin LNG (and Inpex Ichthys will also have some areas) Power stations (Channel Island, Weddell) Industrial facilities, such as the Vopak Fuel Terminal Some maybe less obvious examples: Service stations (bowsers and tanks) LPG refilling areas (eg BCF, BBQs Galore) Laboratories Airports (including aircraft hangars) Workshops (welding bays where acetylene is used) 6

7 Did you know? Flour (grain), white/granulated sugar and cocoa are highly explosive and come under the heading of combustible dusts Some of the worst industrial explosions have been due to combustible dusts. 7 Other examples include coal, citric acid

8 Something to note It is rarely possible by simple examination of a plant or plant design, without extensive experience, to decide which parts of the plant are hazardous areas. More detailed information is necessary and this involves the analysis of the basic properties of the materials present and the possibility of a release occurring. Hazardous area classification is a specialist area. 8

9 Which of these plants contain a hazardous area? 9 Plant A Plant B

10 Classification Hazardous area classification divides areas in to Zones based on the likely frequency and duration of a release, release rate, concentration, velocity and ventilation of the area. Hazardous area classification zones include 10 but this is not the whole picture.

11 Classification Example of Zones for Gases & Vapours AS/NZS Figure ZA.4 11

12 Classification - Jargon Alert! Classification also considers the materials being considered and assigns an equipment group and temperature classification to the area based on the material properties. Temperature class T1, T2, T3..T6 (400 C down to 85 C) How hot the thing gets.. Also known as the autoigntion temperature Equipment/Apparatus or Gas group - IIA, IIB, IIC How much energy it has the spark energy.. IIA is the least onerous, IIC the most 12 And this is the area that gets forgotten about

13 Common myths - Round 1 We will just go with the worst case scenario and say that all equipment installed needs to be IIC T6. Your installation will be very dark as you won t be able to buy a light fitting. But what about hydrogen? IIC gas explosive..but Has an incredibly high autoigntion temperature C, which makes it a T1 requirement Acetylene is a nastier gas Takeaway point - You need to check. It s not always obvious. 13

14 Current trends in classification The classic approach still in use is via examples in AS/NZS Equipment Protection Levels (EPLs) introduced in the last update to the standard Photo Vopak Darwin (vopak.com) 14

15 Current trends in classification What about other areas? (That are not covered in AS/NZS ): Fuel wharves and berths (ship loading and unloading) Diesel areas 15

16 Other areas International standards to the rescue! IP15 Good for fuel wharves and berths (ship loading and unloading) API RP 505 Diesel areas Dispersion Modelling for those other hard to determine areas Gas pipeline pressure relief/venting 16

17 Diesel areas About diesel. Flashpoint is generally 61 C, which makes it a combustible Australian standards only require you to consider hazardous areas for combustible liquids which are being handled above (flashpoint 6 degrees).this is 55 C for diesel 17

18 Diesel areas Manufacturer caution Ullage spaces within tanks Hazards from misting So why talk about it? Some companies are taking a very conservative line and are treating all diesel as a flammable, in case the 55 degree mark is breached But, many diesel installations are classified as non-hazardous. Which way do you go? 18

19 Design and installation Back in the bad old days.. Now.. The design and installation of a hazardous area installation must be completed by competent persons to AS/NZS It involves correct selection of explosion protection techniques and installation requirements for the classified areas. 19

20 Design and installation 20 There are many things to consider: Explosion protection techniques Ambient conditions Cable selection Location of equipment Additional electrical requirements for different protection techniques Certificates of conformity for equipment Information for inclusion within the verification dossier

21 Common myths Round 2 Intrinsically safe areas No such thing All hazardous area equipment is intrinsically safe No it s not. Other protection techniques are often in use Only industrial plants have hazardous areas No again! Also found in education facilities, commercial buildings, etc 21

22 Equipment - Explosion protection techniques There are many different explosion protection techniques. The most common ones are: Flameproof enclosures d Increased safety e Intrinsic safety i Non-sparking n Encapsulation m Special protection s Protection by Enclosure td (used to be DIP) Refer to Sylvania Lighting Information Sheet 22

23 Design and installation Flameproof (Ex d) motor: 23

24 Design and installation Non-sparking (Ex na) light fitting: 24

25 Design and installation Intrinsically safe (Ex i) level transmitter..the one time it s ok to call something intrinsically safe..when it actually is. 25

26 Inspection and maintenance People performing inspections or maintenance shall be competent. Inspections conducted to AS/NZS Initial, detailed grade inspections on completion of installation Maximum timeframe of 4 years between inspections Periodic inspections can be close or visual, however if major defects are found, should be upgraded to detailed inspections Defects must be rectified as soon as practicable 26

27 Inspection and maintenance In Queensland and Victoria, it is mandatory for a third party to complete an inspection of the installation to confirm compliance with standards and that the installation is safe. The inspector will provide a permission to energise when they are happy that the installation is safe and compliant. This is not a legislative requirement in the NT, however many industrial sites will insist on a third party verification of new installations prior to energisation. 27

28 Some of the interesting stuff Why you should use proper flameproof barrier type glands..\..\videos\aplng Cable.mp4 28

29 Some of the interesting stuff Sir Samuel Griffiths Centre hydrogen fuel cell facility Imported European equipment modifications required for Australian standards 29

30 Some of the interesting stuff Laboratory Chemical Waste Collection System Dispersion modelling to reduce zone extents 30

31 Some key takeaways. 1. If you have a hazardous area installation, get competent personnel involved early this saves changes later which are more expensive 2. Use the risk control hierarchy to reduce the size of the zones or the equipment installed within them 3. Hazardous areas is a specialist area if you want to work in this area, get trained and competent 31

32 Further Information Standards Australia Publications HB13 Handbook: Electrical equipment for hazardous areas AS/NZS Explosive atmospheres Part 10.1: Classification of areas Explosive gas atmospheres AS/NZS Explosive atmospheres Part 10.2: Classification of areas Combustible dust atmospheres AS/NZS Explosive atmospheres Part 14: Electrical installations design, selection and erection 32 AS/NZS Explosive atmospheres Part 17: Electrical installations inspections and maintenance

33 33 Questions?