The Executive Summary can be found here: Executive Summary

Solar Turbines is a Caterpillar subsidiary that manufactures and operates gas-turbine engines.
Solar manufactures the world’s most widely used family of mid-sized industrial gas turbines, ranging from 1 to 23 megawatts. More than 16,000 Solar units are installed in more than 100 countries with more than 3 billion operating hours. Solar is a leading provider of energy solutions, featuring an extensive line of gas turbine-powered compressor sets, mechanical drive packages, and generator sets.

Project Background and Objective

The Solar Turbines Ancillary Inlet system provides clean, filtered air to the turbine where it is used in the combustion cycle. This inlet system has a large flange attaching the inlet duct to the turbine intake. The flange is currently sealed by sixty bolts and a liquid gasket. This method of fastening the flange together may create a strong seal but requires up to two hours and two technicians to install or remove the flange during turbine installation, removal, and maintenance.

The objective of the project is to reduce the installation and removal time of the flange by at least 30 minutes. Any additional time saved in the installation process would be beneficial, but thirty minutes was the goal stated by the sponsor as an appropriate benchmark. A review of existing design solutions and currently available off the shelf parts informed our decision to create a two-part solution. This will include designing a quick disconnect method of sealing and disassembling the flange and the replacement of the liquid gasket with a solid one.

Final Design

Requirements of the New Design Include:

Connect the flange and maintain an airtight seal
This will be designed for a 2psi negative pressure in the inlet duct
Reduce the installation and removal time of the flange by a minimum of 30 minutes
Develop an assembly process that is ergonomic for the assembly and removal process
The quick-disconnect solution must fit within the given space of the turbine enclosure
A scaled prototype of the flange must be developed and tested with operating vacuum pressure using the quick-disconnect solution

The designs have been narrowed down to two styles of clamps and a few types of gaskets. The clamps chosen are commercial off-the-shelf products that are rated to withstand forces required to compress selected gaskets to the required thickness. The clamps used will be the Latch-Style Clamp and Undermount Toggle Clamp. These clamps will then be tested a Vacuum Test Platform to time how fast they install and remove a scaled down flange and will also be subject to a pressure/vacuum test to further determine if the clamps will work for the ancillary inlet flange. The clamps are shown connected to the test platform below:

CAD Model of Test Rig

Test Rig - Physical Model

Experimental Testing

The prototype will consist of select clamps and gaskets chosen for testing. These components will be tested on a vacuum test platform that is also a scaled down flange. The two tests that will be performed are comparing assembly and removal time of the top flange and a pressure/vacuum test to ensure an airtight seal at around 2psi. There will be control tests of the current bolt and liquid gasket design as well.

Testing Conditions

The test platform will be a scaled version of the flange
The flanges are thinner due to machine-shop limitations
A vacuum of -2psi gauge pressure will be applied to the platform after flange installation
This will be monitored over a period of 8-12 hours for and leaks

Expectations

The clamps are predicted to save about 5 minutes on the scaled prototype installation and assembly test as compared to the bolts.
The solid gasket is expected to save 5 minutes in assembly time and 10-15 minutes of removal time compared to the liquid gasket
The clamps and solid gasket are expected to perform the same as the bolt and liquid gasket design.

Experimental Testing Results

The undermount toggle clamp and latch style clamp were tested with foam gaskets and were compared to the current flange solution of bolts and Sikaflex(liquid gasket). Manufacturing timed assemble and removal tests proved that the undermount toggle clamps and foam gaskets can save approximately 85% of time when compared to the bolt and Sikaflex design. Vacuum tests were also conducted. The bolts and Sikaflex as well as the undermount toggle clamps and foam gaskets were able to maintain a 4in Hg vacuum for up to 12 hours. The latch-style clamps were unable to hold vacuum when tested with foam gaskets.

Below are pictures of various fasteners and gaskets assembled on the vacuum test rig.

Bolts and Sikaflex

Undermount Toggle Clamp and Foam Gasket

Latch Style Clamp and Foam Gasket

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