(07b) Uwe Vogel

8/10/2019 (07b) Uwe Vogel

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Mrz-10/V4/Uwe Vogel · Stavanger Oil & Gas · 105/03/10 · SAMSON AG · Technical Sales · Uwe Vogel · 1

Functional safety of globe

valves, rotary plug valves,

ball valves and butterfly valves

SAMSON AG - Technical Sales V4 - Uwe Vogel

8/10/2019 (07b) Uwe Vogel



8/10/2019 (07b) Uwe Vogel


Mrz-10/V4/Uwe Vogel · Stavanger Oil & Gas · 3

More than 70 countries

with 50 daughter companies

and 145 sales & engineering offices

with 3,100 employees worldwide

Turnover worldwide > 500 Mio €

SAMSON is represented in:

SAMSON Group worldwide

8/10/2019 (07b) Uwe Vogel




valves, rotary plug valves,

ball valves and butterfly valves

SAMSON AG - Technical Sales V4

Uwe Vogel

8/10/2019 (07b) Uwe Vogel



Change of Standards

IEC

IEC

Yesterday

01.08.2004

Today

IEC

61508

IEC

61511

DIN V

19250

DIN V

19251

VDI/VDE 2180 p2VDI/VDE 2180 p1 VDI/VDE 2180 p3

DIN V 0801

NE 31

IEC

61508

IEC

61511

ANSI/ISA –84.01

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Safety Loops in the process industry – IEC 61508 / 61511

Protection Layers

Safety layer is independent from

Basic Process Control System

Comprises Sensors, Logiksolver,

Valves

Operates in a monitoring – passive

state

No operator interaction

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Risk Assessment – Risk Graph IEC 61508-5

IEC 61 508-5

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Risk Graph Comparison for different standards

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Risk Reduction

P r o c e s s

R i s k

Inherent Process Risk

Ri s k R e d u c t i on

Unacceptable

Region

Tolerable

Region (ALARP)

Broadly AcceptableRegion

P L 1

P L 2

P L 3

Safeguards

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Safety Loops in the process industry – IEC 61508 / 61511

Protection Layers

Safety layer is independent from

Basic Process Control System

Comprises Sensors,

Logiksolver, Valves

Operates in a monitoring –

passive state

No operator interaction

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Demand Modes

Safety function on

demand

Example: Emergency Shut Off Valve

(ESD)

Low Demand Mode

Example: Break in a car

Safety Function

always in operation

High Demand Modeor Continuous Mode

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SIL – Safety Integrity Level

SIL is assigned to the whole loop

• PFD (component) is influenced by

reliability and test intervall

• PFD (total) = (component)

PFD= ½ λDU * Ti

Other factors: SFF (safe failure

fraction), HFT (hardware fault

tolerance)

SIF Safety instrumented function

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Valves in Safety Instrumented Systems (SIS)

Ball Valves

Butterfly Valves

Globe Valves

Rotary Plug Valves

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Statistics – Applicable for Mechanical Systems?

„There are lies, there are damn lies, and then there´sstatistics.“

Mark Twain

„However neutral computers may be, they can neverproduce an objective answer from highly subjective

data.“

Imperato and Mitchell, Acceptable Risks, 1985

“Reliability models are like captured foreign spies; ifyou torture them long enough, they´ll tell youanything.“

Paul Gruhn

Zitiert nach

Paul Gruhn

Safety ShutdownSystems

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Evaluation of failure characteristics

Result: Failure rate , SFF: safe failure fraction(Failure modes, diagnostic coverage factor)

Proven in use

• Based on field data

• Record all failures

• Analyse failure modes

• Evaluation of all possible failures

• Commit to likelihood

• Data from public data bases or from ownfield experience

FMEDA

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Typical Safety related Characteristics

Lambda safe undetected SU = 8.6 * 10-7

Lambda safe detected SD = 0

Lambda dangerous undetected DU= 5.4 * 10-8

Lambda dangerous detected DD = 0

Hardware fault tolerance HFT = 0

Device Type A

Safe failure fraction SFF 94%

Safety related Characteristics (for the calculation)

PFD = ½ * DU * Ti = 2.4 *10-4

= SIL 3 ??

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Hardware Fault Tolerance (HFT)

A final element has a single-channel design, resulting in a hardware failure tolerance

(HFT) = 0.

One failure will result in a non-working valve.

Valves “Proven in use” can be used up to SIL 2

A redundant architecture can cover up to SIL 3

The minimum required hardware failure tolerance may be decreased by one if the following requirements

are met (IEC 61511 - 1 § 11.4.4):

The device is proven in use.Take this into account when selecting devices!

The device only allows process-relevant parameters to be set, e.g. measuring range, upscale or

downscale function in case of failure. Valves do not have any configurable functions. The process-relevant parameters of the device are access-protected, e.g. by jumper or password.

Valves do not have any configurable functions.

The function requires a SIL less than 4.

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Intended use of control valves in safety-instrumented systems

The reliability of mechanical components is significantly affected by the operating conditions by

means of systematic failures and not statistical failure. This needs to be taken into accountwhen selecting and sizing valves.

Safety-instrumented functionDuring normal operation, the signal pressure is applied to the

pneumatic actuator. To meet the requirements of the safety-

instrumented function, the actuator is usually vented by a

solenoid valve. The force of the actuator springs moves thevalve to ist final position, i.e. the valve is either completely

opened or closed.

Reaching the end position of the valve must not be impeded

under any circumstances by mechanical devices, such as

travel stops or handwheels.

Contact with the process media may cause systematic failure and, as a result, affect the safety-related

availability of the safety-instrumented systems. The influence of specific process conditions must

be analyzed and taken into account during sizing and maintenance.

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Avoiding systematic failure

To avoid systematic failures, the user must consider the

following application specific factors besides themanufacturer specifications:

Corrosion (destruction primarily of metals due to

chemical and physical processes)

Material fatigue, e.g. in bellows seals

Wear induced by the process medium

Abrasion (material removed by solids contained in

the process medium) Medium deposits

Aging (damage caused to organic materials, e.g.

plastics or elastomers, by exposure to light and heat)

Chemical attack (organic materials, e.g. plastics or

elastomers, which swell, leach out or decompose due

to exposure to chemicals)

If no experience data exist for the devices used, a visual inspection of the safety

equipment must be performed after an adequate time in operation.

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General Valve Requirements

For each application, the user must specify the following conditions:

Maximum/minimum transit time OPEN CLOSED or CLOSED OPEN

Permissible leakage rate

Maximum/minimum supply pressure

Air capacity available in relation to pressure Connecting pipe cross-sections must be adhered to

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The seat shut-off performance (leakage rate) must be tested at regular intervals by

performing plausibility checks while the process is running

or

measuring leakage rate on a leakage test bench.

The type of test depends on the application

DIN EN 12 266

ANSI FCI 70-2

API 598

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To prevent corrosion of the actuator springs, measures must be taken to prevent water or

moisture from entering the actuator. Such measures include fitting a venting pipe or airpurging of the actuator‘s spring chamber.

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Special Requirements for Globe Valves

If there is a risk of solids contained in the process medium causing

blockage, a strainer must be fitted up stream of the valve.

To reduce friction, it is preferable to use spring-loaded stem packings

Adjustable stem packings are to be tightened by qualified staff only to

prevent the stem from becoming blocked.

Globe valves are typically used for control applications. The plug

performs a linear movement and throttles the flow.

Sometimes control valves are used in sequence with a ball valve in a

safety loop

Safety equipment with fail-open action must not

be operated with strainers.

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It is essential to check the actuator forces to ensure

that the valve can overcome the processpressures to reach its fail-safe position.

The actual actuator forces must not close the valve

against a pressure which is 1.5 times above the

nominal pressure (PN) of the plant or valve.

If this actuator force restriction cannot be

implemented, an excess pressure valve is necessaryfor valves connected in series to prevent that

the permissible operating pressure is exceeded.FFriction

Fclosing

FActuator

Fdelta p

Fweight

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It is essential to observe the prescribed direction of flow (arrow on the

valve body) of globe valves.

Pressure from the wrong side of the plug may prevent, that the valve

can open

Safety control and shut-off valve

combination for gas fired boilers

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Special Requirements for Ball Valves

Note for ball valves that higher initial breakaway torques arise as the differential

pressure of the process medium rises, requiring higher actuator torques

Media, especially degreasing, swelling and fibrous media, may affect the torque

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Special Requirements for Ball Valves

The operating conditions, e.g. switching interval and the medium

temperature, have an effect on the torques

The mounting of the valve and actuator is of vital importance

The permissible torques for the ball valve shaft, shaft adapter and

bridge have been verified by the manufacturer. As a result, the

maximum torque of the actuator (air or spring torque) must not

exceed these torques under any circumstances.

Torque limits according DIN EN ISO 5211

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Special Requirements for Butterfly Valves

On sizing actuators for butterfly valves, note that the actuator must

provide sufficient torque to overcome the breakaway torque andclosing torque in closed position as well as the dynamic torque in

open position.

On mounting the actuator on the butterfly valve, the breakaway

torque of the butterfly valve in relation to the differential pressure

and the permissible torque of the butterfly valve shaft must be

observed.

Note that high dynamic torques can arise at high differential

pressures in the process medium, pushing open the butterfly disc

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Special Requirements for Butterfly Valves

Media, especially degreasing, swelling and fibrous media, may

affect the torque

The operating conditions, e.g. switching interval and the medium

temperature, have an effect on the torques

The mounting of the valve and actuator is of vital importance

The permissible torques for the butterfly valve shaft, shaft adapter

and bridge have been verified by the manufacturer. As a result, themax. torque of the actuator (air or spring torque) must not exceed

these torques under any circumstances.

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Proof tests and service life

The proof test interval and the extent of the test lie within the operator‘s responsibility.

This must be documented correspondingly.

During the proof test, suitable means must be used to test the control valve to ensure its

proper functioning. Worn components must be replaced by original spare parts from the

manufacturer.

The maximum service life must be specified.

It is recommended to summarizethe requirements of the proof test

in a checklist.

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Mechanical and pneumatic installation

During mechanical and pneumatic installation, the mounting and operating instructions

of the corresponding device must be observed.

The pneumatic connection must only be connected to instrument air networks that meet

the quality requirements in accordance with ISO 8573-1:2001, Class 3 or 4.

The prescribed mounting position of the devices

must be observed.

Booster valve ports not connected by pipe or hose

must be protected properly against dirt, water etc.

from entering the device by using appropriate

filters.

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Electrical installation

Only cables with the prescribed outer diameter of the cable glands may be used.

For EExi circuits the electrical cable data must comply with the data taken as the basis during

planning.

Cable glands and cover screws must be fastened tightly to ensure that the degree of

protection is met.

Only devices with suitable equipotential bonding may be connected.

The installation regulations for the respective explosion protection measures must be

observed.

Prior to start-up, the voltage must be checked to ensure that it meets the permissible range.

The effect of disturbances to lines must be checked, especially

Disturbance caused by EMC influence

or

Disturbance caused by capacitance influence when long cable are used

risk that a solenoid valve remains energized

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Installation of valves

Control valves must be installed free of stress and with low degrees

of vibration.

After installation, the flange joints must be checked for leaks.

The pipeline must be flushed prior to installing the valve.

To ensure that the valve functions properly, the pipeline must be

designed to be straight and without any manifolds or disturbances

for a distance of at least six times the pipe size (DN) upstream anddownstream of the valve.

It must be checked whether the mounting position of the control

valve complies with the manufacturer‘s specifications (operating

instructions).

The devices used must be checked to ensure they are suitable for

use under the prevailing ambient conditions (temperature, humidity)

While installing the control valves, sufficient space must be left to

remove the valve for maintenance.

The wiring and function of devices must be documented in a wiring

plan.

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Competence in Functional Safety


valves, rotary plug valves,all

valves and butterfly valves

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(07b) Uwe Vogel

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