In this paper we describe a congruence pair for a strongly $\pi$-inverse $r$-semigroup and in this way we obtain a generalization of a result of Petrich [5]. A semigroup $S$ is is $\pi$-\emph{regular} if for every $a\in S$ there exists a positive integer $m$ such that $a^m\in a^mSa^m$. We shall denote by $\operatorname{Reg}S$ the set of all regular elements of $S$. An element $a'$ is an inverse for $a$ if $a=aa'a$ and $a'=a'aa'$. As usual, we shall denote by $V(a)$ the set of all inverses of $a$. If $A$ is $a$ subset of $S$, then $V(a)=\Cup_{a\in A}V(a)$. A semigroup $S$ is $\pi$-\emph{orthodox} if $S$ is $\pi$-regular, and the set $E(S)$ of all, idempotents of $S$ is a subsemigroup of $S$ [1]. A semigroup $S$ is \emph{strongly $\pi$-inverse} if it is $\pi$-regular and the idempotents commute [1].