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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549


FORM 11-K

(Mark One)


ý

ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2001

OR

o TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                              to                             

Commission file numbers: 33-25419, 33-64058 and 333-75256


A.    Full title of the plan and the address of the plan, if different from that of the issuer named below:

Airgas, Inc. 401(k) Plan

B.    Name of the issuer of the securities held pursuant to the plan and the address of its principal executive office:

Airgas, Inc.
259 North Radnor-Chester Road, Suite 100
Radnor, PA 19087-5283





REQUIRED INFORMATION

(1)
Financial Statements:

        The following financial statements, including Independent Auditors' Report thereon of Airgas, Inc. 401(k) Plan, are submitted herewith:

        The schedule for which provision is made in the applicable accounting regulations of the Securities and Exchange Commission is included in the aforementioned financial statements of the Airgas, Inc. 401(k) Plan.

(2)
Exhibits:

23.1
Consent of KPMG LLP


SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the Plan Administrator has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

    AIRGAS, INC. 401(k) PLAN
        (Name of Plan)

 

 

BY:

 

/s/  
ROGER F. MILLAY      
Roger F. Millay
Senior Vice President—Finance and Chief Financial Officer

 

 

BY:

 

/s/  
TODD R. CRAUN      
Todd R. Craun
Vice President—Law and Secretary

DATED: June 26, 2002



AIRGAS, INC. 401(k) PLAN

Financial Statements and
Supplementary Schedule

December 31, 2001 and 2000

(With Independent Auditors' Report Thereon)



AIRGAS, INC. 401(k) PLAN

Table of Contents

 
  Page
Independent Auditors' Report   1

Statements of Net Assets Available for Benefits,
December 31, 2001 and 2000

 

2

Statements of Changes in Net Assets Available for Benefits,
Years ended December 31, 2001 and 2000

 

3

Notes to Financial Statements

 

4

Schedule:

 

 

1—Schedule of Assets Held for Investment Purposes, December 31, 2001

 

9

Independent Auditors' Report

The Plan Administrator
Airgas, Inc. 401(k) Plan:

        We have audited the accompanying statements of net assets available for benefits of the Airgas, Inc. 401(k) Plan as of December 31, 2001 and 2000, and the related statements of changes in net assets available for benefits for the years then ended. These financial statements are the responsibility of the Plan's management. Our responsibility is to express an opinion on these financial statements based on our audits.

        We conducted our audits in accordance with auditing standards generally accepted in the United States of America. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit also includes assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

        In our opinion, the financial statements referred to above present fairly, in all material respects, the net assets available for benefits of the Airgas, Inc. 401(k) Plan at December 31, 2001 and 2000, and the changes in net assets available for benefits for the years then ended, in conformity with accounting principles generally accepted in the United States of America.

        Our audits were performed for the purpose of forming an opinion on the basic financial statements taken as a whole. The supplemental schedule of assets held for investment purposes as of December 31, 2001, is presented for the purpose of additional analysis and is not a required part of the basic financial statements but is supplementary information required by the Department of Labor's Rules and Regulations for Reporting and Disclosure Under the Employee Retirement Income Security Act of 1974. This supplemental schedule is the responsibility of the Plan's management. The supplemental schedule has been subjected to the auditing procedures applied in the audits of the basic financial statements and, in our opinion, is fairly stated in all material respects in relation to the basic financial statements taken as a whole.

Philadelphia, Pennsylvania
June 10, 2002

1



AIRGAS, INC. 401(k) PLAN

Statements of Net Assets Available for Benefits

December 31, 2001 and 2000

 
  2001
  2000
Investments   $ 146,213,934   $ 127,753,554
   
 
Receivables:            
  Employee contributions     906,101     1,031,817
  Employer contributions     254,514     293,373
   
 
    Total receivables     1,160,615     1,325,190
   
 
Participant loans receivable     5,813,189     5,961,386
   
 
Net assets available for benefits   $ 153,187,738   $ 135,040,130
   
 

See accompanying notes to financial statements.

2



AIRGAS, INC. 401(k) PLAN

Statements of Changes in Net Assets Available for Benefits

Years ended December 31, 2001 and 2000

 
  2001
  2000
 
Additions:              
  Additions to net assets attributable to:              
    Investment income:              
      Net appreciation (depreciation) in fair value of investments   $ 6,731,001   $ (25,211,824 )
      Interest and dividends     4,043,521     12,494,171  
   
 
 
        Total investment income (loss), net     10,774,522     (12,717,653 )
   
 
 
  Contributions:              
    Employee     13,410,302     21,541,344  
    Employer     5,873,191     5,965,433  
   
 
 
        Total contributions     19,283,493     27,506,777  
   
 
 
  Deductions:              
    Benefits paid to participants     (11,746,534 )   (13,777,439 )
    Administrative fees     (163,873 )   (155,820 )
   
 
 
        Total deductions     (11,910,407 )   (13,933,259 )
   
 
 
  Transfers from other benefit plans         1,634,337  
   
 
 
        Net additions     18,147,608     2,490,202  
   
 
 
  Net assets available for benefits:              
    Beginning of year     135,040,130     132,549,928  
   
 
 
    End of year   $ 153,187,738   $ 135,040,130  
   
 
 

See accompanying notes to financial statements.

3



AIRGAS, INC. 401(k) PLAN

Notes to Financial Statements

December 31, 2001 and 2000

(1) Description of the Plan

        The following description of the Airgas, Inc. 401(k) Plan (the Plan) provides general information only. Participants should refer to the Plan agreement for more complete information.

4


(2) Merger of 401(k) Plans

        During 2000, in connection with acquisitions completed by the Company, there were transfers in from certain 401(k) plans of acquired companies of approximately $1.6 million.

(3) Summary of Significant Accounting Policies

5


6


(4) Investments

        The following investments represent 5% or more of the net assets available for benefits at December 31, 2001 and 2000:

 
  2001
  2000
Airgas Common Stock Fund   $ 38,556,132   $ 17,922,364
Vanguard U.S. Growth Fund     23,785,570     33,502,706
Vanguard 500 Index Fund     14,895,927     14,402,139
Vanguard Wellington Fund     19,471,844     17,376,741
Vanguard Retirement Savings Trust     24,809,345     21,667,221

7


        During the years ended December 31, 2001 and 2000, the net appreciation (depreciation) in the fair value of investments (including realized gains and losses) was as follows:

 
  2001
  2000
 
Airgas Common Stock Fund   $ 21,551,972   $ (19,383,952 )
Mutual Funds     (14,820,971 )   (5,827,872 )
   
 
 
Net appreciation (depreciation) in fair value of investments   $ 6,731,001   $ (25,211,824 )
   
 
 

(5) Tax Status

        The Internal Revenue Service (IRS) has determined and informed the Company by a letter dated January 31, 2000, that the Plan is designed in accordance with applicable sections of the Internal Revenue Code and is therefore exempt from federal income taxes. The Plan has been amended since receiving the determination letter. However, the Plan administrator believes that the Plan is designed and is currently being operated in compliance with the applicable requirements of the Internal Revenue Code and continues to be exempt from federal income taxes.

(6) Related-Party Transactions

        The Plan invests in shares of mutual funds (Vanguard funds) managed by an affiliate of Vanguard Fiduciary Trust Company, who acts as trustee for the Plan. Investment transactions of the Plan qualify as party-in-interest transactions, but are not prohibited transactions.

(7) Plan Termination

        Although it has not expressed any intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. Upon termination of the Plan, participants would remain fully vested in all amounts credited to their accounts under the Plan.

(8) Defaulted Loans

        During the year ended December 31, 2001, there were 143 participants who were in default of their loans, including 4 participants who were active employees. Loans in the amount of $774,797 were in default and included in participant loans as of December 31, 2001.

        During the year ended December 31, 2000, there were 49 participants who were in default of their loans, including 47 participants who were active employees. Loans in the amount of $125,897 were in default and included in participant loans as of December 31, 2000.

(9) Subsequent Event

        On February 28, 2002, the Company purchased the majority of Air Products and Chemicals, Inc.'s U.S. packaged gas business. Approximately 1,100 employees associated with the acquired business were eligible to participate in the Plan effective March 1, 2002.

8


Schedule 1


AIRGAS, INC. 401(k) PLAN

Schedule of Assets Held for Investment Purposes

December 31, 2001

Number of
Shares

  Investments *
  Fair Value
    Common stock:      
2,550,009       Airgas Common Stock Fund   $ 38,556,132

 

 

Mutual funds:

 

 

 
111,453       Vanguard Explorer Fund     6,721,719
206,611       Vanguard International Growth Fund     3,101,224
1,261,834       Vanguard U.S. Growth Fund     23,785,570
140,674       Vanguard 500 Index Fund     14,895,927
714,301       Vanguard Wellington Fund     19,471,844
327,075       Vanguard LifeStrategy Growth Fund     5,700,919
248,539       Vanguard LifeStrategy Moderate Growth Fund     3,959,231
119,122       Vanguard LifeStrategy Conservative Growth Fund     1,674,849
72,346       Vanguard LifeStrategy Income Fund     930,374
257,081       Vanguard Total Bond Market Index Fund     2,606,800

 

 

Vanguard Retirement Savings Trust, 5.98%

 

 

24,809,345

 

 

Employee loans, 6.75% to 11.00%

 

 

5,813,189
       

 

 

Total assets held for investment purposes

 

$

152,027,123
       

*
Investment transactions of the Plan qualify as party-in-interest transactions.

See accompanying independent auditors' report.

9




QuickLinks

REQUIRED INFORMATION
SIGNATURES
AIRGAS, INC. 401(k) PLAN Table of Contents
AIRGAS, INC. 401(k) PLAN Statements of Net Assets Available for Benefits December 31, 2001 and 2000
AIRGAS, INC. 401(k) PLAN Statements of Changes in Net Assets Available for Benefits Years ended December 31, 2001 and 2000
AIRGAS, INC. 401(k) PLAN Notes to Financial Statements December 31, 2001 and 2000
AIRGAS, INC. 401(k) PLAN Schedule of Assets Held for Investment Purposes December 31, 2001