GE POWER TIL 2319

PRODUCT SERVICE Publish Date: 04 NOVEMBER 2021

Compliance Category - S
Timing Code - 2

TECHNICAL INFORMATION LETTER

EXCESSIVE GAS FUEL FLOW AT STARTUP DUE TO INCORRECT CONTROL CONSTANT
APPLICATION
Heavy-duty gas turbine frames 6B, 6F, 7E, 9E, 7F, and 9F shipped prior to 2007. This also applies to some additional
gas turbine frames with more limited production like 6A, 7B, 7C, and 9B shipped prior to 2007.

PURPOSE
To inform users of a possible controls application software issue or incorrect constant setting that may affect excessive
gas fuel protection during startup attempts. Additionally, to recommend the affected units to follow recommendations in
this TIL.

COMPLIANCE CATEGORY
M - Maintenance Identifies maintenance guidelines or best practices for reliable equipment operation.

C - Compliance Required Identifies the need for action to correct a condition that, if left uncorrected, may result in reduced
equipment reliability or efficiency. Compliance may be required within a specific operating time.
A - Alert Failure to comply with the TIL could result in equipment damage or facility damage. Compliance is
mandated within a specific operating time.
S - Safety Failure to comply with this TIL could result in personal injury. Compliance is mandated within a
specific operating time.
TIMING CODE
1 Prior to Unit Startup / Prior to Continued Operation (forced outage condition)
2 At First Opportunity (next shutdown)
3 Prior to Operation of Affected System
4 At First Exposure of Component
5 At Scheduled Component Part Repair or Replacement.
6 Next Scheduled Outage

© 2021 General Electric Company

The proprietary information published in this Technical Information Letter is offered to you by GE in consideration of its ongoing sales and service relationship with
your organization. However, since the operation of your plant involves many factors not within our knowledge, and since operation of the plant is in your control
and ultimate responsibility for its continuing successful operation rests with you, GE specifically disclaims any responsibility for liability based on claims for damage
of any type, i.e. direct, consequential or special that may be alleged to have been incurred as result of applying this information regardless of whether it is claimed
that GE is strictly liable, in breach of contract, in breach of warranty, negligent, or is in other respects responsible for any alleged injury or damage sustained by
your organization as a result of applying this information. This Technical Information Letter contains proprietary information of General Electric Company and is
furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall
not be reproduced or distributed in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE. All rights reserved.

Date Printed: 04 NOVEMBER 2021

BACKGROUND DISCUSSION
As part of the gas turbine startup, it is critical to accurately control the amount of gas fuel flow during the ignition
sequence. The stop valve (s) isolate the gas fuel flow and regulate the supply pressure, the stop speed ratio valve (SRV)
regulates the inter-cavity pressure (P2) to a pre-determined pressure setting and the gas control valves (GCVs) operating
off a supply manifold control fuel flow to the combustion system. Figure 1 shows a basic fuel system sketch, the valve
configuration differs based on combustion system and site requirements.

Figure 1: Basic Gas Fuel System Schematic

During a recent gas turbine startup attempt on gas fuel, the inter-cavity pressure transmitters (typically, 96FG-2) were
inadvertently left in isolation mode post-maintenance work. Upon startup, the SRV and GCV opened to admit gas fuel to
the combustors during the ignition sequence. Since the inter-cavity pressure transmitters were valved-out in isolation,
the pressure transmitters showed no increase in inter-cavity gas pressure. Consequently, the SRV regulator continued
increasing the valve stroke to a high value and admitted excessive fuel to the gas turbine as shown in Figure 2.

Figure 2. SRV high opening leading to Exhaust Overtemperature Trip

© 2021 General Electric Company

The proprietary information published in this Technical Information Letter is offered to you by GE in consideration of its ongoing sales and service relationship with
your organization. However, since the operation of your plant involves many factors not within our knowledge, and since operation of the plant is in your control
and ultimate responsibility for its continuing successful operation rests with you, GE specifically disclaims any responsibility for liability based on claims for damage
of any type, i.e. direct, consequential or special that may be alleged to have been incurred as result of applying this information regardless of whether it is claimed
that GE is strictly liable, in breach of contract, in breach of warranty, negligent, or is in other respects responsible for any alleged injury or damage sustained by
your organization as a result of applying this information. This Technical Information Letter contains proprietary information of General Electric Company and is
furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall
not be reproduced or distributed in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE. All rights reserved.

Date Printed: 04 NOVEMBER 2021

Although there was no negative safety related deflagration in this specific event, excessive fuel flow at ignition sequence
can lead to uncontrolled combustion events which can cause injury to personnel along with severe damage to exhaust
duct and other downstream components.
During a fleet software review, there were two findings:
1) Some gas turbine application software may not have the excessive gas flow trip protection properly connected to the
pre-ignition trip sequence.
2) Some gas turbines may not have the maximum SRV pre-ignition trip set at the correct level. To protect against the
scenario of inter-cavity pressure transmitters valved-out , automated pre-ignition trip protection software for new gas
turbines was added around the 1970s to trip the turbine prior to ignition if the SRV stroke gets too high. PSSB
20140102A-R1: Excessive Gas Flow at Start-up discusses this in some more detail.

RECOMMENDATIONS
Due to the critical nature of the excessive fuel flow protection to the safe and reliable operation of the gas turbine, GE
recommends users to confirm that the SRV trip sequence is properly implemented in the software and to review correct
settings are used for the high stroke limit.

1. Verify correct sequence is installed at site:

a. Identify the Startup Fuel Flow Excessive (typically L2SFT) protection exists in the gas turbine’s software. If not, then
it’s recommended to update the software with this protection. Contact your GE representative for details.
b. Ensure that Startup Gas Fuel Flow Excessive (typically L2SFTG) drives a gas turbine trip. For example, as shown in
Figure 3, L2SFTG>L2SFT>L4PSTX2>L4PST>L4T where L4T is the Master Protective Trip. If not, reach out to your GE
representative.

Figure 3: Fuel Flow Excessive Protection Sequence

© 2021 General Electric Company

The proprietary information published in this Technical Information Letter is offered to you by GE in consideration of its ongoing sales and service relationship with
your organization. However, since the operation of your plant involves many factors not within our knowledge, and since operation of the plant is in your control
and ultimate responsibility for its continuing successful operation rests with you, GE specifically disclaims any responsibility for liability based on claims for damage
of any type, i.e. direct, consequential or special that may be alleged to have been incurred as result of applying this information regardless of whether it is claimed
that GE is strictly liable, in breach of contract, in breach of warranty, negligent, or is in other respects responsible for any alleged injury or damage sustained by
your organization as a result of applying this information. This Technical Information Letter contains proprietary information of General Electric Company and is
furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall
not be reproduced or distributed in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE. All rights reserved.

Date Printed: 04 NOVEMBER 2021

2. Verify correct constant setting in software:
a. Verify the as-running value for the Startup Fuel Stroke High Setpoint (LK60FSGH) in the application software is at or
below the ‘Upper Spec Limit’ in Table 1. If LK60FSGH is at or below the ‘Upper Spec Limit’, no action is required.
b. If the value is above the ‘Upper Spec Limit’, ensure a 15-meter exclusion zone is maintained around the gas turbine
exhaust flow path during the gas fuel startup ignition sequence and reach out to your GE representative to review startup
data and determine an acceptable level.

Table 1: LK60FSGH settings per gas turbine frame

The TIL can be considered complete once both recommendations above are completed. Until this TIL is complete, a 15
meter exclusion zone must be maintained around the gas turbine exhaust flow path during the gas fuel startup ignition
sequence.

© 2021 General Electric Company

The proprietary information published in this Technical Information Letter is offered to you by GE in consideration of its ongoing sales and service relationship with
your organization. However, since the operation of your plant involves many factors not within our knowledge, and since operation of the plant is in your control
and ultimate responsibility for its continuing successful operation rests with you, GE specifically disclaims any responsibility for liability based on claims for damage
of any type, i.e. direct, consequential or special that may be alleged to have been incurred as result of applying this information regardless of whether it is claimed
that GE is strictly liable, in breach of contract, in breach of warranty, negligent, or is in other respects responsible for any alleged injury or damage sustained by
your organization as a result of applying this information. This Technical Information Letter contains proprietary information of General Electric Company and is
furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall
not be reproduced or distributed in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE. All rights reserved.

Date Printed: 04 NOVEMBER 2021

PLANNING INFORMATION

Compliance
• Compliance Category: S
• Timing Code: 2

Manpower Skills
Qualified controls technician or GE controls field engineer.

Parts
N/A

Special Tooling
N/A

Reference Documents
PSSB 20140102A-R1: Excessive Gas Flow at Start-up

Scope of Work
This work can be performed while operating within 8 hours by reviewing the application software.

If software changes are required to address recommendation 1., contact your GE representative as software change
instruction may need to be provided by GE prior to site implementation, if feasible.

If software changes are required to address recommendation 2., this will require reviewing previous startup data and
simply performing a controls constant change.

TIL DISPOSITION

Disposition of TILs should be entered in local records and also in GE Power ServiceNow. Follow the below instructions for entering the
disposition record;

• Log into the Power ServiceNow at https://gepowerpac.service-now.com/til_new/ using your GE SSO number and password.

• Select "TIL Disposition".

• Click on the TIL for the serial number you want to update.

• Choose the most appropriate "Disposition Status" and enter "Disposition Notes".

• Click "Save".

Contact your local GE Services representative for assistance or for additional information

© 2021 General Electric Company

The proprietary information published in this Technical Information Letter is offered to you by GE in consideration of its ongoing sales and service relationship with
your organization. However, since the operation of your plant involves many factors not within our knowledge, and since operation of the plant is in your control
and ultimate responsibility for its continuing successful operation rests with you, GE specifically disclaims any responsibility for liability based on claims for damage
of any type, i.e. direct, consequential or special that may be alleged to have been incurred as result of applying this information regardless of whether it is claimed
that GE is strictly liable, in breach of contract, in breach of warranty, negligent, or is in other respects responsible for any alleged injury or damage sustained by
your organization as a result of applying this information. This Technical Information Letter contains proprietary information of General Electric Company and is
furnished to its customer solely to assist that customer in the installation, testing, operation and/or maintenance of the equipment described. This document shall
not be reproduced or distributed in whole or in part nor shall its contents be disclosed to any third party without the written approval of GE. All rights reserved.

Date Printed: 04 NOVEMBER 2021