Can you analyse the cost behaviour between in-house and outsourced equipment maintenance?


The company in question is a JV of India’s leading oil marketing and gas distribution companies. The company’s product portfolio includes Compressed Natural Gas (CNG), catering to more than ~14 Lacs CNG vehicles and Piped Natural Gas (PNG), catering to more than ~21 Lacs domestic PNG customers.


Compressors and dispensers are the principal equipment used in a CNG station for filling CNG in vehicle tanks. The operational costs of these types of equipment are primarily maintenance-related. Therefore, the company in question needs assistance in designing a framework for strategic decision-making to enable accurate gauging of maintenance costs of in–house vs. outsourced compressors and dispensers.

In addition, given the company’s huge customer base, the availability of stations during working hours is paramount. This renders the correct computation of costs a challenging process compounded by the additional burden of resource requirements during the maintenance of compressors and dispensers.


To evaluate the cost of maintenance, the compressors and dispensers are initially categorised into in–house and outsourced categories. These outsourced compressors/ dispensers are further subcategorised into AMC (machines under warranty) and CAMC (after the machines’ warranty has expired).

The costs so ascertained are then allocated to the different makes/ models of the compressors/dispensers based on capacity, which is the most reasonable and scientific basis, using the cause-and-effect principle in accordance with the relevant Cost Accounting Standards issued by the Institute of Cost Accountants of India. This trend analysis was performed and studied on three years of cost data. Identification of cost elements and the cost computation of compressors/ dispensers’ category

specific are as follows:

Cost Elements

Cost Computation

In–house maintenance

Direct Employee Cost

Includes the salary/cost to the company (CTC) of station technicians deputed for the operation and maintenance of compressors/dispensers.

Cost of Spares and Consumables

Includes the consumption cost of spares, lubricants, oil, CO2, etc., for the maintenance of compressors/dispensers.

​Repair and Maintenance Cost (R&M)

​It includes the following costs:

  • Expenses booked under Repair & Maintenance GL accounts

  • Employees costs pertaining to the maintenance department (identified through the cost centre)

  • Overheads pertaining to the maintenance department (identified through the cost centre)

Cost of Contract/Procurement

It includes costs that pertain to the procurement department (identified through the cost centre):

  • Employees cost

  • Depreciation expenses

  • Insurance cost

  • Overheads

Stores and Inventory Carrying Cost

It includes the following costs:

  • Employees costs pertaining to the stores’ department (identified through the cost centre)

  • Overheads pertaining to the stores’ department (identified through the cost centre)

  • Inventory carrying cost computed based on the average stock multiplied by the company’s basic return on investment %

​Other Cost

Other costs include vehicles hired for in-house equipment maintenance.

Outsourced Maintenance

Outsourcing Charges

These are the annual maintenance charges (AMC).

Cost of Contract/Procurement

Procurement department's responsibility is to initiate and complete the AMC/CAMC tendering process. The cost formula is the same as that of in-house maintenance, and the cost is segregated into in-house and outsourced equipment based on the equipment’s capacity.

​Maintenance Cost

It includes the employees’ costs pertaining to the maintenance department (identified through the cost centre). The cost is segregated into in-house and outsourced equipment based on the equipment’s maintenance frequency.

Hiring of Vehicle Cost

​It includes vehicles hired for outsourced equipment maintenance.


Weighted average cost/Equipment/Month analysis was observed for all three years. It was concluded that equipment’s in–house maintenance activity is more economical compared to equipment’s outsourced CAMC maintenance activity. Another observation was that following the procurement of the new equipment (Outsourced AMC category), the maintenance activity was at a minimal cost given the machines are new, under warranty, and require minimum maintenance.

Weighted Average Cost/Equipment/Month (3 Years) in relative terms

​In-house (after the machines’ warranty has expired)

​Outsourced CAMC(after the machines’ warranty has expired)

Outsourced AMC (machines under warranty)






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