Exhibit 3.3

CERTIFICATE OF LIMITED PARTNERSHIP
OF
UCO GENERAL PARTNER, LP

     This Certificate of Limited Partnership, dated June 13, 2006, has been duly executed and is filed pursuant to Section 17-201 of the Delaware Revised Uniform Limited Partnership Act (the "Act”) to form a limited partnership under the Act.

     1. Name. The name of the limited partnership is “UCO General Partner, LP”.

     2. Registered Office; Registered Agent. The address of the registered office required to be maintained by Section 17-104 of the Act is:

Corporation Trust Center
1209 Orange Street
Wilmington, Delaware 19801

The name and the address of the registered agent for service of process required to be maintained by Section 17-104 of the Act are:

The Corporation Trust Company
Corporation Trust Center
1209 Orange Street
Wilmington, Delaware 19801

     3. General Partner. The name and the business, residence or mailing address of the general partner are:

UCO GP, LLC
4444 Brittmoore Road
Houston, Texas 77041

     EXECUTED as of the date written first above.

UCO GP, LLC, its General Partner
By:	/s/ J. Michael Anderson
	J. Michael Anderson
	Authorized Person