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Dear David Many tganks for the useful inputs. I request you to please share any reference document from OEM procedure as it would be extremely useful for me to propose the change Thanks again for the feedback

Dear All Recently while stopping a 55 MW Generator Drive Steam Turbine, as per normal shutdown procedure given by Turbine OEM, Turbine load was feduced to 4 MW and Generator Breaker Opened. However Turbine Speed reached Overspeed Trip limit but unfortunately Turbine couldn't be tripped due to...

Dear All Many thanks for the extremely useful info from all of you. Special Thanks to electricpete for the detailed explanation Dear crshears Please note that in the attached Curves, the lowest curve is Load Curve which increases exponentially with Speed throughout acceleration phase. (Torque...

Dear Gr8blu In the attached Motor Curves, it can be seen that from 70% to 95% of rated Speed (0.7 - 0.95 on Speed Axis) the differential b/w Motor Starting Torque and Load Torque (lower most line in Curve) sharply increases i.e. there is sharp rise in Staring Torque which increases from around...

Dear All Many thanks for useful inputs from all of you. Your valuable cooperation is highly appreciated Dear Gr8blu Regarding your point "The difference between Motor Torque and Load Torque is the acceleration torque", I am still unable to understand what exactly controls this Motor Torque...

Dear Johnny What I am thinking is while startup there is actually no Torque demand from Compressor Side. Its up to the Prime Mover Capability that how much angular acceleration it can impart to the Inertia of Compressor Train in ramping up to the rated speed

Dear Johnny Many Thanks for your feedback. Regarding your point "The motor is capable of developing 2.5 times full load torque. But, the coupling would only see this much torque if the driven machine was offering that much resistance", this is exactly what I was thinking initially. But May I...

Dear All We are facing problem of Coupling Failure on an Electric Motor Drive Centrifugal Compressor Train. The layout is as follows Motor - Gear Box - LP Compressor - HP Compressor The Motor is Squirrel Cage type 3 Phase Induction Motor (2 Pole, 2967 RPM, 50 Hz) started Direct On Line. As per...

Dear All We are facing problem of repeated Coupling Failures on a Centrifugal Compressor Train driven by a 2967 RPM, 2 pole, 3 phase, 50 Hz Squirrel Cage Induction Motor. Attached is the Screenshot of Motor Curves showing Motor can develop up to 2.5 times full load torque during startup which is...

For clarity of explanation, I have attached curve obtained from GE Reference document which explains the situation mentioned in Pint No.1 in above...

Dear stgrme Many thanks for extremely useful reply. Your idea about Boiler trip and cracks in 1st Nozzle is absolutely correct. For sake of clarity of situation, please note the Turbine under discussion is Mechanical Drive Turbine in Petrochemical Plant with normal Power of 40-45 MW, 8 Stage...

Dear JJ First of all many thanks for useful info regarding Axial Retention methodology for blades in this type of Turbines. 02 out of 05 failed blades have been tested at metallurgical lab. I have still not received the details but as per initial feedback, lab results didn't find any evidence...

Dear Tugboat MT Inspection has been donehttps://files.engineering.com/getfile.aspx?folder=064e50e9-b67e-4d38-8168-5fe9063d1183&file=Blade_Root_Crack_(Stage-I).jpg

Dear JJ Attached are the Pictures of Blade Roots from Inlet as well as Exhaust Side with Blades installed in Wheel Slots. May be possible to get any clue of how blades are retained in Axial Direction. May be something to do with the...

Dear JJ Regarding you point about about Blade Retention, I believe you are referring to retention in Axial direction. Physically looking at the blades I am unable to find any mechanism for retention in Axial Direction (like twist locks in GE heavy Duty Gas Turbines). I need to further check...

Dear JJ & EdStainless Thanks for your useful inputs The Turbine has Electronic Overspeed Trip System and there is no Mechanical Overspeed Trip. Trip Test is done at reduced speed by simulation. The Blades are retained by Shrouds at Outer Dia (group of 06 Blades in one Shroud Segment)...

Dear All Recently during planned outage of a Steam Turbine, we have observed cracks on the Roots of some Blades in 1st Wheel. The Blade Roots are dovetail design. Turbine is Multi Stage (08 Stages) Extraction/Condensing Impulse Turbine (Rateau Turbine.) Live Steam conditions are 61 barg & 430...

Hi Johnny Just to clarify your concern regarding Seal Flush Plan, refer to the attached Snapshot of Seal Flush System P&I Diagram Your comments are very useful as all your guess is correct. There is no direct measurement of Seal Chamber Pressure. On Suction side there is only Pressure Gage and...

Dear Johnny Sorry for incomplete info. The Flushing Plan used is API 53B. The normal Seal Chamber Pressure is 3.5 barg and can go maximum up to 7.7 Barg. Mating Ring is Reaction Bonded Silicon Carbide & Primary Ring is Carbon. The product Temperature is 2570Celsius. Normal operating Barrier...

Hi Johnny Thanks for your valuable inputs. I have attached pictures of Seal Components showing observations noted on latest Seal disassembledhttps://files.engineering.com/getfile.aspx?folder=96309044-7b76-498d-939b-e3e5d11ca535&file=Removed_Seal_Observations.pdf